Begin adding some docs to elfutils

Begin adding some docs to elfutils

- Added doc/README
- Updated doc/ChangeLog
- Added a eu-readelf manpage based on the one from binutils.
- Added a brand new manpage for eu-elfclassify the new utility.
- Add some new files in the doc directory and sync makefile with upstream.
- Reenable the compilation of doc directory.
- Disable sgml file building
- Build man pages the automake way

Since V1
- Put man pages in the proper directories.
- Added copy of Gnu Free Documentation License
- Modified eu-readelf.1 man page to match the supported options.

Signed-off-by: Ben Woodard <woodard@redhat.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>