Add hover documentation for reserved keywords #15052

Job	Run time
spelling	15s
build_node (macos-latest)	2m 34s
lint_node	38s
lint_ruby	29s
build_node (ubuntu-latest)	2m 29s
Verify Jekyll website builds	10s
build_node (windows-latest)	7m 37s
Ruby 3.4 on ubuntu-latest	10m 47s
Ruby 3.2 on ubuntu-latest	11m 58s
Ruby 3.3 on ubuntu-latest	11m 33s
Ruby 3.1 on macos-latest	7m 10s
Ruby 3.3 on windows-latest	24m 4s
Ruby 3.2 on macos-latest	7m 44s
Ruby 3.4 on windows-latest	21m 42s
Ruby 3.1 on windows-latest	25m 26s
Ruby 3.1 on ubuntu-latest	12m 2s
Ruby 3.2 on windows-latest	24m 9s
Ruby 3.3 on macos-latest	6m 25s
Ruby 3.4 on macos-latest	6m 33s
	3h 3m 45s

Provide feedback