* Makefile.md: distribute HACKING.md rather than the now nonexistant HACKING
* Makefile.md: distribute HACKING.md rather than the now nonexistant HACKING

hercules-team/augeas,ptoscano/augeas,hercules-team/augeas,pevalme/augeas,mchf/augeas,kunkku/augeas,mlichvar/augeas,pevalme/augeas,lutter/augeas,ptoscano/augeas,mlichvar/augeas,ptoscano/augeas,kunkku/augeas,lutter/augeas,manandbytes/augeas,mlichvar/augeas,kunkku/augeas,lutter/augeas,mchf/augeas,manandbytes/augeas,pevalme/augeas