Update Changelog

Add:

* Move POST /{username}/action/{action} to simply POST /{username} (go-gitea#18045) (go-gitea#18046)
* Fix delete u2f keys bug (go-gitea#18040) (go-gitea#18042)
* Reset Session ID on login (go-gitea#18018) (go-gitea#18041)
* Prevent off-by-one error on comments on newly appended lines (go-gitea#18029) (go-gitea#18035)

Signed-off-by: Andrew Thornton <art27@cantab.net>

CHANGELOG.md

@@ -4,10 +4,14 @@ This changelog goes through all the changes that have been made in each release
 without substantial changes to our git log; to see the highlights of what has
 been added to each release, please refer to the [blog](https://blog.gitea.io).
 
-## [1.15.8](https://github.com/go-gitea/gitea/releases/tag/v1.15.8) - 2021-12-19
+## [1.15.8](https://github.com/go-gitea/gitea/releases/tag/v1.15.8) - 2021-12-20
 
 * BUGFIXES
-  * Stop printing 03d after escaped characters in logs (#18030) (#18034) 
+  * Move POST /{username}/action/{action} to simply POST /{username} (#18045) (#18046)
+  * Fix delete u2f keys bug (#18040) (#18042)
+  * Reset Session ID on login (#18018) (#18041)
+  * Prevent off-by-one error on comments on newly appended lines (#18029) (#18035)
+  * Stop printing 03d after escaped characters in logs (#18030) (#18034)
   * Reset locale on login (#18023) (#18025)
   * Fix reset password email template (#17025) (#18022)
   * Fix outType on gitea dump (#18000) (#18016)