Add config for default branch name (#171)

Co-authored-by: Thomas Miceli <27960254+thomiceli@users.noreply.github.com>

docs/index.md

@@ -35,7 +35,7 @@ Written in [Go](https://go.dev), Opengist aims to be fast and easy to deploy.
 ## System requirements
 
 [Git](https://git-scm.com/download) is obviously required to run Opengist, as it's the main feature of the app.
-Version **2.20** or later is recommended as the app has not been tested with older Git versions.
+Version **2.28** or later is recommended as the app has not been tested with older Git versions and some features would not work.
 
 [OpenSSH](https://www.openssh.com/) suite if you wish to use Git over SSH.