Bump google-protobuf from 4.28.0 to 4.28.2 in /docs

Bumps [google-protobuf](https://github.com/protocolbuffers/protobuf) from 4.28.0 to 4.28.2.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Changelog](https://github.com/protocolbuffers/protobuf/blob/main/protobuf_release.bzl)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

---
updated-dependencies:
- dependency-name: google-protobuf
  dependency-type: indirect
...

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

docs/Gemfile.lock

@@ -15,16 +15,16 @@ GEM
     ffi (1.17.0-x86_64-darwin)
     ffi (1.17.0-x86_64-linux-gnu)
     forwardable-extended (2.6.0)
-    google-protobuf (4.28.0)
+    google-protobuf (4.28.2)
       bigdecimal
       rake (>= 13)
-    google-protobuf (4.28.0-arm64-darwin)
+    google-protobuf (4.28.2-arm64-darwin)
       bigdecimal
       rake (>= 13)
-    google-protobuf (4.28.0-x86_64-darwin)
+    google-protobuf (4.28.2-x86_64-darwin)
       bigdecimal
       rake (>= 13)
-    google-protobuf (4.28.0-x86_64-linux)
+    google-protobuf (4.28.2-x86_64-linux)
       bigdecimal
       rake (>= 13)
     http_parser.rb (0.8.0)