docs: updated contributors guide

CONTRIBUTING.md

@@ -2,28 +2,23 @@
 
 We are open to, and grateful for, any contributions made by the community. By contributing to axios, you agree to abide by the [code of conduct](https://github.com/axios/axios/blob/master/CODE_OF_CONDUCT.md).
 
-### Code Style
+## Code Style
 
 Please follow the [node style guide](https://github.com/felixge/node-style-guide).
 
-### Commit Messages
+## Commit Messages
 
-Commit messages should be verb based, using the following pattern:
+Please follow [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/)
 
-- `Fixing ...`
-- `Adding ...`
-- `Updating ...`
-- `Removing ...`
-
-### Testing
+## Testing
 
 Please update the tests to reflect your code changes. Pull requests will not be accepted if they are failing on [Travis CI](https://travis-ci.org/axios/axios).
 
-### Documentation
+## Documentation
 
 Please update the [docs](README.md) accordingly so that there are no discrepancies between the API and the documentation.
 
-### Developing
+## Developing
 
 - `grunt test` run the jasmine and mocha tests
 - `grunt build` run webpack and bundle the source
@@ -33,34 +28,34 @@ Please update the [docs](README.md) accordingly so that there are no discrepanci
 
 Please don't include changes to `dist/` in your pull request. This should only be updated when releasing a new version.
 
-### Releasing
+## Releasing
 
 Releasing a new version is mostly automated. For now the [CHANGELOG](https://github.com/axios/axios/blob/master/CHANGELOG.md) requires being updated manually. Once this has been done run the commands below. Versions should follow [semantic versioning](http://semver.org/).
 
 - `npm version <newversion> -m "Releasing %s"`
 - `npm publish`
 
-### Running Examples
+## Running Examples
 
 Examples are included in part to allow manual testing.
 
 Running example
 
 ```bash
-$ npm run examples
+> npm run examples
 # Open 127.0.0.1:3000
 ```
 
 Running sandbox in browser
 
 ```bash
-$ npm start
+> npm start
 # Open 127.0.0.1:3000
 ```
 
 Running sandbox in terminal
 
 ```bash
-$ npm start
-$ node ./sandbox/client
+> npm start
+> node ./sandbox/client
 ```