Replace the dependency list in the README to mention libxrandr instead
of libxinerama since that's the default value of the MULTIMON variable
in config.mk
Remove xext and xft as a dependency since they are not currently used
and probably haven't been used a while.
Also remove freetype2 from the pkg-config list, while it is required by
pangocairo it should be included from the pkg-config --cflags call.
Move README to docs/dunst.pod to be used as man page. Write a README with building instructions and dependencies. Remove INSTALL as it's no longer necessary.
