made the pull-request gate configurable: added watcher.pullRequestGate (default true); set false for plain-git origins without pull-request refs, so requirePullRequest gates are ignored and gated branches build on new commits; added the PR-doc

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/gittally/commands/InitCommand.kt

@@ -152,6 +152,9 @@ class InitCommand(
               pollInterval: 10s
               # max commit age for new origin branches to be pulled automatically
               newBranchMaxAge: 5d
+              # honor branches.<name>.requirePullRequest; set false for a plain git origin
+              # without pull-request refs (refs/pull/*/head) — gated branches then build on new commits
+              pullRequestGate: true
 
             # Per-branch build configuration.
             # Use "default" as the fallback for all branches not listed explicitly.