Add link to home page on swagger ui (#12601)

* Add link to home page on swagger ui

Signed-off-by: a1012112796 <1012112796@qq.com>

* translate

* Apply review suggestion

* Move to right, Thanks @silverwind

* tweaks

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: John Olheiser <john.olheiser@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

options/locale/locale_en-US.ini

@@ -21,6 +21,7 @@ signed_in_as = Signed in as
 enable_javascript = This website works better with JavaScript.
 toc = Table of Contents
 licenses = Licenses
+return_to_gitea = Return to Gitea
 
 username = Username
 email = Email Address