Add manual trigger button for repository index regeneration

Adds workflow_dispatch event to allow manually triggering the
index regeneration workflow from GitHub UI.

To use: Go to Actions tab → Regenerate Repository Indexes → Run workflow

Author: craig8

.github/workflows/regenerate-indexes.yml

@@ -8,6 +8,7 @@ on:
       - '**.jar'
       - 'cnf/releaserepo/**/*.jar'
       - 'dependencies/**/*.jar'
+  workflow_dispatch:
 
 jobs:
   regenerate-indexes: