Fix html documentation warnings.

See #15346.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74689 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix ribbon documentation warnings.

See #15346.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74690 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775