Create an "Editor-only" section in the online class reference

This helps to find such classes without digging
through the rest of the class reference.
Editor-only classes can still be found under
your normal "Node" and "Resource" types.

This also fixes a typo and a missed case from the recent platform docs PR.

.github/workflows/static_checks.yml

@@ -82,7 +82,7 @@ jobs:
 
       - name: Documentation checks
         run: |
-          doc/tools/make_rst.py --dry-run --color doc/classes modules platforms
+          doc/tools/make_rst.py --dry-run --color doc/classes modules platform
 
       - name: Style checks via clang-format (clang_format.sh)
         run: |