docs: Gitea is the home (D-65 amended)

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

README.md

@@ -536,8 +536,7 @@ The examples state rules in their own words with the paragraph cited
 
 ## Home and consumers
 
-The canonical home is `https://github.com/swaits/bookspec`; the mirror is
-`https://git.swaits.com/swaits/bookspec`. wanderbooks consumes this
+The home is `https://git.swaits.com/swaits/bookspec`. wanderbooks consumes this
 repository as a git dependency pinned to a commit, so its `just check`
 keeps running every example through `bookspec_checker::examples()`. The
 vendored authorities that `spec/` cites (`docs/spec/sources/`) and