docs: add v15 release

Author: escapedcat

README.md

@@ -198,6 +198,7 @@ Features will only be applied to the current main version.
 
 | Release                                                                          | Inital release | End-of-life |
 | -------------------------------------------------------------------------------- | -------------- | ----------- |
+| [v15](https://github.com/conventional-changelog/commitlint/releases/tag/v15.0.0) | 17.11.2021     | 17.11.2022  |
 | [v14](https://github.com/conventional-changelog/commitlint/releases/tag/v14.0.0) | 26.10.2021     | 26.10.2022  |
 | [v13](https://github.com/conventional-changelog/commitlint/releases/tag/v13.0.0) | 24.05.2021     | 24.05.2022  |
 | [v12](https://github.com/conventional-changelog/commitlint/releases/tag/v12.0.0) | 23.02.2021     | 23.02.2022  |