Doc changes.

Updated some wxOSX related information.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75159 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
spelling and styling fixes

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75160 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775