Don't use capital "H" in the header archives names.

This is inconsistent with "docs" and is just strange.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74961 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Update SF release notes for 3.0.0-rc1.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74962 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775