Update changelog

Author: Seldaek

CHANGELOG.md

@@ -3,11 +3,14 @@
 All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
-## [master]
+## [main]
 
-  * Changed: updated licenses list to SPDX 3.11
   ...
 
+## [1.5.5] 2020-12-03
+
+  * Changed: updated licenses list to SPDX 3.11
+
 ## [1.5.4] 2020-07-15
 
   * Changed: updated licenses list to SPDX 3.9
@@ -86,7 +89,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
     - Classname: `Updater` -> `SpdxLicensesUpdater`
   * Changed: validation via regex implementation instead of lexer.
 
-[master]: https://github.com/composer/spdx-licenses/compare/1.5.4...master
+[main]: https://github.com/composer/spdx-licenses/compare/1.5.5...main
+[1.5.5]: https://github.com/composer/spdx-licenses/compare/1.5.4...1.5.5
 [1.5.4]: https://github.com/composer/spdx-licenses/compare/1.5.3...1.5.4
 [1.5.3]: https://github.com/composer/spdx-licenses/compare/1.5.2...1.5.3
 [1.5.2]: https://github.com/composer/spdx-licenses/compare/1.5.1...1.5.2