feat: add the prepare plugin hook

BREAKING CHANGE: Committing or creating files in the `publish` plugin hook is not supported anymore and now must be done in the `prepare` hook

Plugins with a `publish` hook that makes a commit or create a file that can be committed must use the `prepare` hook.

docs/usage/configuration.md

@@ -155,6 +155,18 @@ Define the [generate notes plugin](plugins.md#generatenotes-plugin).
 
 See [Plugins configuration](plugins.md#configuration) for more details.
 
+### prepare
+
+Type: `Array`, `String`, `Object`
+
+Default: `['@semantic-release/npm']`
+
+CLI argument: `--prepare`
+
+Define the list of [prepare plugins](plugins.md#prepare-plugin). Plugins will run in series, in the order defined in the `Array`.
+
+See [Plugins configuration](plugins.md#configuration) for more details.
+
 ### publish
 
 Type: `Array`, `String`, `Object`

docs/usage/plugins.md

@@ -28,6 +28,14 @@ Plugin responsible for generating release notes.
 
 Default implementation: [@semantic-release/release-notes-generator](https://github.com/semantic-release/release-notes-generator).
 
+### prepare plugin
+
+Plugin responsible for preparing the release, including:
+- Creating or updating files such as `package.json`, `CHANGELOG.md`, documentation or compiled assets.
+- Create and push commits
+
+Default implementation: [npm](https://github.com/semantic-release/npm#prepare).
+
 ### publish plugin
 
 Plugin responsible for publishing the release.