build: bump rake from 13.0.0 to 13.0.1 in /docs

Bumps [rake](https://github.com/ruby/rake) from 13.0.0 to 13.0.1.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](https://github.com/ruby/rake/compare/v13.0.0...v13.0.1

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

docs/Gemfile.lock

@@ -223,7 +223,7 @@ GEM
       forwardable-extended (~> 2.6)
     public_suffix (3.1.1)
     rainbow (3.0.0)
-    rake (13.0.0)
+    rake (13.0.1)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)