Properly capitalize "GitHub" (#1033)

Author: veyndan

CONTRIBUTING.md

@@ -23,7 +23,7 @@ To share either bug or features, [create an issue here](https://github.com/inter
 
 Before we begin, if you don't already have, download [git](https://git-scm.com/downloads ) and [node.js](https://nodejs.org/en/download/ ). You may look at relevant tutorials to set them up according to your operating system.
 
- - Open the [wayback machine browser extension github page](https://github.com/internetarchive/wayback-machine-webextension/ ) and fork the project.
+ - Open the [wayback machine browser extension GitHub page](https://github.com/internetarchive/wayback-machine-webextension/ ) and fork the project.
  - Open the terminal and navigate to the directory where you wish to clone the project using   
     `cd <Address-to-the-directory>`
  - Clone the project and navigate to working directory by typing the commands
@@ -56,7 +56,7 @@ Once you have cloned the repository to your local machine (this would work with
 `npm test`
  - Read the [Testing Guide](TESTING_GUIDE.md) for details.
 
-### Push the changes to Github
+### Push the changes to GitHub
 
  - Open your git terminal
  - Create a new branch for every feature you add, or every set of bugs you fix and more to that branch using  
@@ -69,7 +69,7 @@ Once you have cloned the repository to your local machine (this would work with
 To learn how to write a good commit message, please see [https://chris.beams.io/posts/git-commit/](https://chris.beams.io/posts/git-commit/)
  - Push the changes to the repository using  
 `git push -u origin <branch-name>`
- - Open the main github repository, and create a Pull Request. (You will see an option when you open the repository)
+ - Open the main GitHub repository, and create a Pull Request. (You will see an option when you open the repository)
  - Review the PR title, and make it meaningful. For example  
 `"Fix 399: Popup background now Black"`
 

TESTING_GUIDE.md

@@ -43,7 +43,7 @@ To avoid `no-undef` errors that may occur with external global variables or func
 
 ## Updating Dependencies ##
 
-Github's Dependabot may alert potential security issues in dependencies.
+GitHub's Dependabot may alert potential security issues in dependencies.
 
 To view and fix these issues:
 

webextension/about.html

@@ -119,7 +119,7 @@ <h3>Mobile Apps</h3>
         </p>
 
         <h3>Credits</h3>
-        <p><a href="https://github.com/internetarchive/wayback-machine-webextension" target="_blank">Source Code on Github</a></p>
+        <p><a href="https://github.com/internetarchive/wayback-machine-webextension" target="_blank">Source Code on GitHub</a></p>
         <p>
           Carl Gorringe <a href="https://github.com/cgorringe" target="_blank">@cgorringe</a><br>
           Anish Kumar Sarangi <a href="https://github.com/anishsarangi" target="_blank">@anishsarangi</a><br>