chore: add contributing guide

.gitignore

@@ -1,6 +1,5 @@
 *.log
 .DS_Store
 node_modules
-projects
 coverage
 dist

README.md

@@ -69,6 +69,19 @@ Design and build websites that are decoupled from the CMS. This means you can ea
 - [How it works](https://gridsome.org/docs/how-it-works)
 - [How to deploy](https://gridsome.org/docs/deployment)
 
+## How to contribute
+
+Install [Node.js 8.3](https://nodejs.org/en/download/) or higher and [Yarn](https://yarnpkg.com/lang/en/docs/install/). It's also recommended to install [Lerna](https://www.npmjs.com/package/lerna) globally.
+
+1. Clone this repository.
+2. Create a new Gridsome project inside the `/projects` folder.
+3. Enter the new project folder and run `yarn` (or `lerna bootstrap` if installed).
+4. The project will now use the local packages when you run `gridsome develop`
+
+To use `@gridsome/cli` in the repo as a global command. Enter the `/packages/cli` folder and run `npm link`.
+
+Yarn will add dependencies from your test projects to the root `yarn.lock` file. So you should not commit changes in that file unless you have added dependencies to any of the core packages. If you need to commit it, remove your projects from the `/projects` folder temporary and run `yarn` or `lerna bootstrap` in the root folder. Yarn will then clean up the lock file with only core dependencies. Commit the file and move your projects back and run `yarn` or `lerna bootstrap` again to start developing.
+
 ## Roadmap for v1.0
 
 - [x] `*.vue` pages and templates
@@ -77,8 +90,8 @@ Design and build websites that are decoupled from the CMS. This means you can ea
 - [x] Multi-process HTML rendering
 - [x] Lazy-loading images and pages
 - [x] Pagination
-- [ ] Taxonomies
 - [ ] Plugin API
+- [ ] Taxonomies
 - [ ] Service Worker
 - [ ] Documentation
 - [ ] Guides

projects/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore