Removed multiple dead links (#349)

* removed dead links under web app -> react

* removed dead links under web app -> others

* removed dead link under python -> web app

* removed dead link under openCV

* removed two dead links and an incomplete tutorial link under desktop applications

* added tutorial under openCV, mistakenly removed earlier

Author: alabhyajindal

README.md

@@ -1,4 +1,5 @@
 # Project Based Learning
+
 [![Gitter](https://badges.gitter.im/practical-tutorials/community.svg)](https://gitter.im/practical-tutorials/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
 
 A list of programming tutorials in which aspiring software developers learn how to build an application from scratch. These tutorials are divided into different primary programming languages. Tutorials may involve multiple technologies and languages.
@@ -101,6 +102,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
   - [Part 6: Input and output](https://briancallahan.net/blog/20210819.html)
   - [Part 7: Arrays](https://briancallahan.net/blog/20210822.html)
   - [Part 8: Strings, forward references, and conclusion](https://briancallahan.net/blog/20210826.html)
+
 ### Network programming
 
 - Let's Code a TCP/IP Stack
@@ -112,6 +114,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
   - [Part 5: TCP Retransmission](http://www.saminiir.com/lets-code-tcp-ip-stack-5-tcp-retransmission/)
 
 - Programming concurrent servers
+
   - [Part 1 - Introduction](https://eli.thegreenplace.net/2017/concurrent-servers-part-1-introduction/)
   - [Part 2 - Threads](https://eli.thegreenplace.net/2017/concurrent-servers-part-2-threads/)
   - [Part 3 - Event-driven](https://eli.thegreenplace.net/2017/concurrent-servers-part-3-event-driven/)
@@ -200,13 +203,11 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [Build an HTML Calculator with JS](https://medium.freecodecamp.org/how-to-build-an-html-calculator-app-from-scratch-using-javascript-4454b8714b98)
 - [Build Snake using only JavaScript, HTML & CSS](https://www.freecodecamp.org/news/think-like-a-programmer-how-to-build-snake-using-only-javascript-html-and-css-7b1479c3339e/)
 
-
 ### Mobile Application:
 
 - [Build a React Native Todo Application](https://egghead.io/courses/build-a-react-native-todo-application)
 - [Build a React Native Application with Redux Thunk](https://medium.com/@alialhaddad/how-to-use-redux-thunk-in-react-and-react-native-4743a1321bd0)
 
-
 ### Web Applications:
 
 #### React:
@@ -217,9 +218,6 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [React Tutorial: Cloning Yelp](https://www.fullstackreact.com/articles/react-tutorial-cloning-yelp/)
 - [Build a Full Stack Movie Voting App with Test-First Development using Mocha, React, Redux and Immutable](https://teropa.info/blog/2015/09/10/full-stack-redux-tutorial.html)
 - [Build a Twitter Stream with React and Node](https://scotch.io/tutorials/build-a-real-time-twitter-stream-with-node-and-react-js)
-- Build a Serverless MERN Story App with Webtask.io
-  - [Part 1](https://scotch.io/tutorials/build-a-serverless-mern-story-app-with-webtask-io-zero-to-deploy-1)
-  - [Part 2](https://scotch.io/tutorials/build-a-serverless-mern-story-app-with-webtask-io-zero-to-deploy-2)
 - [Build A Simple Medium Clone using React.js and Node.js](https://medium.com/@kris101/clone-medium-on-node-js-and-react-js-731cdfbb6878)
 - [Integrate MailChimp in JS](https://medium.freecodecamp.org/how-to-integrate-mailchimp-in-a-javascript-web-app-2a889fb43f6f)
 - [Build A Chrome Extension with React + Parcel](https://medium.freecodecamp.org/building-chrome-extensions-in-react-parcel-79d0240dd58f)
@@ -253,6 +251,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
   - [Part 2](https://houssein.me/progressive-angular-applications)
 - [Build a Google+ clone with Django and AngularJS (Angular 1.x)](https://thinkster.io/django-angularjs-tutorial)
 - Build A Beautiful Real World App with Angular 8 :
+
   - [Part I](https://medium.com/@hamedbaatour/build-a-real-world-beautiful-web-app-with-angular-6-a-to-z-ultimate-guide-2018-part-i-e121dd1d55e)
   - [Part II](https://medium.com/@hamedbaatour/build-a-real-world-beautiful-web-app-with-angular-8-the-ultimate-guide-2019-part-ii-fe70852b2d6d)
 
@@ -292,9 +291,6 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
   - [Part 1](https://bitsofco.de/bitsofcode-pwa-part-1-offline-first-with-service-worker/)
   - [Part 2](https://bitsofco.de/bitsofcode-pwa-part-2-instant-loading-with-indexeddb/)
   - [Part 3](https://bitsofco.de/bitsofcode-pwa-part-3-push-notifications/)
-- Build A Support Ticket Application With AdonisJs
-  - [Part 1](https://scotch.io/tutorials/build-a-support-ticket-application-with-adonisjs)
-  - [Part 2](https://scotch.io/tutorials/build-a-support-ticket-application-with-adonisjs-part-2)
 - [Build A Native Desktop App with JS](https://medium.freecodecamp.org/build-native-desktop-apps-with-javascript-a49ede90d8e9)
 - Build a Powerful API with NodeJs,GraphQL and Hapi
   - [Part I](https://medium.com/@wesharehoodies/how-to-setup-a-powerful-api-with-nodejs-graphql-mongodb-hapi-and-swagger-e251ac189649)
@@ -313,10 +309,6 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 
 ### Desktop Application:
 
-- Build a Music Player with React & Electron
-  - [Part 1](https://scotch.io/tutorials/build-a-music-player-with-react-electron-i-setup-basic-concepts)
-  - [Part 2](https://scotch.io/tutorials/build-a-music-player-with-react-electron-ii-making-the-ui)
-  - [Part 3](https://scotch.io/tutorials/build-a-music-player-with-react-electron-iii-bringing-it-all-together)
 - [Build A Desktop Chat App with React and Electron](https://medium.freecodecamp.org/build-a-desktop-chat-app-with-react-electron-and-chatkit-744d168e6f2f)
 
 ### Miscellaneous:
@@ -371,7 +363,6 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
 - [Build a RESTful Microservice in Python](http://www.skybert.net/python/developing-a-restful-micro-service-in-python/)
 - [Microservices with Docker, Flask, and React](https://testdriven.io/)
 - [Build A Simple Web App With Flask](https://pythonspot.com/flask-web-app-with-python/)
-- [Build a RESTful API with Flask – The TDD Way](https://scotch.io/tutorials/build-a-restful-api-with-flask-the-tdd-way)
 - [Create A Django API in under 20 minutes](https://codeburst.io/create-a-django-api-in-under-20-minutes-2a082a60f6f3)
 - Build a Community-driven delivery application with Django, Postgres and JavaScript
   - [Part 1](https://www.ashwinhariharan.tech/blog/thinking-of-building-a-contact-tracing-application-heres-what-you-can-do-instead/)
@@ -627,6 +618,7 @@ To get started, simply fork this repo. Please refer to [CONTRIBUTING.md](CONTRIB
   - [Part 4](https://pwy.io/en/posts/learning-to-fly-pt4/)
 
 ## Scala:
+
 - [Simple actor-based blockchain](https://www.freecodecamp.org/news/how-to-build-a-simple-actor-based-blockchain-aac1e996c177/)
 - [No Magic: Regular Expressions](https://rcoh.svbtle.com/no-magic-regular-expressions)