Disable release:guard_clean in Rakefile

The doc generation task creates man pages that make the working tree
dirty, which causes guard_clean to fail during rake release.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hsbt

Rakefile

@@ -25,3 +25,5 @@ task :doc do
 end
 
 task build: :doc
+
+Rake::Task["release:guard_clean"].clear