Documentation/HtmlNav/index.html: Update pointers.
* Source/DocMakefile (before-clean, after-clean): Move obj out of the
way so it isn't removed when cleaning docs.
* Tools/DocMakefile: Idem.
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@20183 72102866-910b-0410-8b05-ffd578937521