CHANGELOG: add missing entries (#6899)

[skip ci]

CHANGELOG.md

@@ -23,6 +23,8 @@ All notable changes to Gogs are documented in this file.
 ### Fixed
 
 - Unable to use LDAP authentication on ARM machines. [#6761](https://github.com/gogs/gogs/issues/6761)
+- Invalid character in `Access-Control-Allow-Credentials` response header. [#4983](https://github.com/gogs/gogs/issues/4983)
+- Mysterious `ssh: overflow reading version string` errors from builtin SSH server. [#6882](https://github.com/gogs/gogs/issues/6882)
 
 ### Removed