feat: add success and fail notification plugins

- Allow `publish` plugins to return an `Object` with information related to the releases
- Add the `success` plugin hook, called when all `publish` are successful, receiving a list of release
- Add the `fail` plugin hook, called when an error happens at any point, receiving a list of errors
- Add detailed message for each error

docs/extending/plugins-list.md

@@ -5,6 +5,8 @@
 - [@semantic-release/github](https://github.com/semantic-release/github)
   - [verifyConditions](https://github.com/semantic-release/github#verifyconditions): Verify the presence and the validity of the GitHub authentication and release configuration
   - [publish](https://github.com/semantic-release/github#publish): Publish a [GitHub release](https://help.github.com/articles/about-releases)
+  - [success](https://github.com/semantic-release/github#success): Add a comment to GitHub issues and pull requests resolved in the release
+  - [fail](https://github.com/semantic-release/github#fail): Open a GitHub issue when a release fails
 - [@semantic-release/npm](https://github.com/semantic-release/npm)
   - [verifyConditions](https://github.com/semantic-release/npm#verifyconditions): Verify the presence and the validity of the npm authentication and release configuration
   - [publish](https://github.com/semantic-release/npm#publish): Publish the package on the npm registry
@@ -25,6 +27,8 @@
   - [analyzeCommits](https://github.com/semantic-release/exec#analyzecommits): Execute a shell command to determine the type of release
   - [verifyRelease](https://github.com/semantic-release/exec#verifyrelease): Execute a shell command to verifying a release that was determined before and is about to be published.
   - [generateNotes](https://github.com/semantic-release/exec#analyzecommits): Execute a shell command to generate the release note
-  - [publish](https://github.com/semantic-release/exec#publish): Execute a shell command to publish the release.
+  - [publish](https://github.com/semantic-release/exec#publish): Execute a shell command to publish the release
+  - [success](https://github.com/semantic-release/exec#success): Execute a shell command to notify of a new release
+  - [fail](https://github.com/semantic-release/exec#fail): Execute a shell command to notify of a failed release
 
 ## Community plugins

docs/usage/configuration.md

@@ -59,7 +59,7 @@ Default: `repository` property in `package.json` or [git origin url](https://git
 
 CLI arguments: `-r`, `--repository-url`
 
-The git repository URL
+The git repository URL.
 
 Any valid git url format is supported (See [Git protocols](https://git-scm.com/book/en/v2/Git-on-the-Server-The-Protocols)).
 
@@ -75,7 +75,7 @@ CLI arguments: `-t`, `--tag-format`
 
 The [Git tag](https://git-scm.com/book/en/v2/Git-Basics-Tagging) format used by **semantic-release** to identify releases. The tag name is generated with [Lodash template](https://lodash.com/docs#template) and will be compiled with the `version` variable.
 
-**Note**: The `tagFormat` must contain the `version` variable and compile to a [valid Git reference](https://git-scm.com/docs/git-check-ref-format#_description).
+**Note**: The `tagFormat` must contain the `version` variable exactly once and compile to a [valid Git reference](https://git-scm.com/docs/git-check-ref-format#_description).
 
 ### dryRun
 

docs/usage/plugins.md

@@ -34,6 +34,18 @@ Plugin responsible for publishing the release.
 
 Default implementation: [npm](https://github.com/semantic-release/npm#publish) and [github](https://github.com/semantic-release/github#publish).
 
+### success plugin
+
+Plugin responsible for notifying of a new release.
+
+Default implementation: [github](https://github.com/semantic-release/github#success).
+
+### fail plugin
+
+Plugin responsible for notifying of a failed release.
+
+Default implementation: [github](https://github.com/semantic-release/github#fail).
+
 ## Configuration
 
 Plugin can be configured by specifying the plugin's module name or file path directly as a `String` or within the `path` key of an `Object`.