Bump rack from 2.0.8 to 2.2.3 in /docs (#162)

Bumps [rack](https://github.com/rack/rack) from 2.0.8 to 2.2.3.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.8...2.2.3)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -88,7 +88,7 @@ GEM
       activesupport (>= 3.1)
     parallel (1.19.1)
     public_suffix (4.0.1)
-    rack (2.0.8)
+    rack (2.2.3)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.1)
       ffi (~> 1.0)