add gitea refs

Signed-off-by: ahuston-0 <aliceghuston@gmail.com>
Reviewed-on: https://<censored>/ahuston-0/hydra/pulls/1

doc/manual/src/plugins/README.md

@@ -100,6 +100,15 @@ Create jobs based on open Gitea pull requests
 
 - `gitea_authorization.<repo-owner>`
 
+## Gitea refs
+
+Hydra plugin for retrieving the list of references (branches or tags) from
+Gitea following a certain naming scheme.
+
+### Configuration options
+
+- `gitea_authorization.<repo-owner>`
+
 ## GitHub pulls
 
 Create jobs based on open GitHub pull requests