Updates some documentation, sparked from issue #3230.
I cannot test the build instructions myself, but assume they will work (what is there now doesn't work regardless).
The command
find . -path '*/.git*' -prune -o -type f -exec grep makefile\\. {} \; -print
shows only 2 more files that reference the old makefile.* files:
cd src; $(MAKE) -f makefile.unix bitcoind
cd src; $(MAKE) -f makefile.unix clean
cd src; $(MAKE) -f makefile.unix test_bitcoin
./contrib/debian/rules
src/makefile.osx (Expat).
./contrib/debian/changelog