state clearly that the entire contents of generated files is generated; put special...

state clearly that the entire contents of generated files is generated; put special {{{ and }}} markers around the generated sections (these are special and extra-convenient for ViM but can probably be used to at least go to the end/beginning/other extremeity of the generated block from any other decent editor)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54219 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775