Add contributing information and move development section

The contributing information is copied from `CONTRIBUTING.md`.

docs/SUMMARY.md

@@ -5,8 +5,6 @@
   * [Usage](/README.md#usage)
   * [License](/README.md#license)
 
-* [Development](dev/README.md)
-
 * [Styles](styles/README.md)
   * [Using CSS Classes](styles/classes.md)
 
@@ -22,3 +20,4 @@
   * [Using Global Style Overrides](examples/global_overrides.md)
 
 * [Contributing](contributing/README.md)
+  * [Development setup](contributing/development.md)

docs/contributing/README.md

@@ -0,0 +1,42 @@
+## Contributing
+
+### Commit Subjects
+
+If your patch **changes the API or fixes a bug** please use one of the
+following prefixes in your commit subject:
+
+- `[fixed] ...`
+- `[changed] ...`
+- `[added] ...`
+- `[removed] ...`
+
+That ensures the subject line of your commit makes it into the
+auto-generated changelog. Do not use these tags if your change doesn't
+fix a bug and doesn't change the public API.
+
+Commits with changed, added, or removed, must be reviewed by another
+collaborator.
+
+#### When using `[changed]` or `[removed]`...
+
+Please include an upgrade path with example code in the commit message.
+If it doesn't make sense to do this, then it doesn't make sense to use
+`[changed]` or `[removed]` :)
+
+### Docs
+
+Please update the README with any API changes, the code and docs should
+always be in sync.
+
+### Development
+
+- `npm start` runs the dev server to run/develop examples
+- `npm test` will run the tests.
+- `scripts/test` same as `npm test` but keeps karma running and watches
+  for changes
+
+### Build
+
+Please do not include the output of `scripts/build` in your commits, we
+only do this when we release. (Also, you probably don't need to build
+anyway unless you are fixing something around our global build.)

docs/dev/README.md → docs/contributing/development.md

@@ -1,4 +1,4 @@
-# Development
+### Development setup
 
 `react-modal` uses `make` to build and publish new versions and documentation.
 
@@ -7,21 +7,21 @@ It works as a checklist for the future releases to keep everything updated such
 
 The minimun works as a normal `npm script`.
 
-## Usage
+#### Usage
 
 Once you clone `react-modal`, you can run `sh bootstrap.sh` to check
 and download dependencies not managed by `react-modal` such as `gitbook-cli`.
 
 It will also show information about the current versions of `node`, `npm`,
 `yarn` and `jq` available.
 
-## List of `npm` commands:
+#### List of `npm` commands:
 
     $ npm start -s or yarn start  # to run examples
     $ npm run tests
     $ npm run lint
 
-## List of `make` commands:
+#### List of `make` commands:
 
     $ make help           # show all make commands available
     $ make deps           # npm install, gitbook plugins...