Add note about the availability of contrib/mac for the macaddr data type.
Add note about the availability of contrib/mac for the macaddr data type.

edespino/gpdb,randomtask1155/gpdb,xuegang/gpdb,yuanzhao/gpdb,edespino/gpdb,foyzur/gpdb,royc1/gpdb,xinzweb/gpdb,royc1/gpdb,foyzur/gpdb,janebeckman/gpdb,lisakowen/gpdb,adam8157/gpdb,rvs/gpdb,atris/gpdb,Chibin/gpdb,rvs/gpdb,atris/gpdb,greenplum-db/gpdb,Quikling/gpdb,arcivanov/postgres-xl,adam8157/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,foyzur/gpdb,Quikling/gpdb,CraigHarris/gpdb,edespino/gpdb,Chibin/gpdb,Postgres-XL/Postgres-XL,lintzc/gpdb,rvs/gpdb,kmjungersen/PostgresXL,zeroae/postgres-xl,snaga/postgres-xl,Quikling/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,lisakowen/gpdb,kmjungersen/PostgresXL,Postgres-XL/Postgres-XL,rubikloud/gpdb,jmcatamney/gpdb,tangp3/gpdb,rubikloud/gpdb,0x0FFF/gpdb,snaga/postgres-xl,jmcatamney/gpdb,yazun/postgres-xl,tangp3/gpdb,chrishajas/gpdb,Chibin/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,postmind-net/postgres-xl,janebeckman/gpdb,techdragon/Postgres-XL,lisakowen/gpdb,chrishajas/gpdb,Postgres-XL/Postgres-XL,CraigHarris/gpdb,foyzur/gpdb,randomtask1155/gpdb,ashwinstar/gpdb,ahachete/gpdb,lpetrov-pivotal/gpdb,lpetrov-pivotal/gpdb,yazun/postgres-xl,ovr/postgres-xl,cjcjameson/gpdb,tangp3/gpdb,atris/gpdb,xuegang/gpdb,tpostgres-projects/tPostgres,CraigHarris/gpdb,randomtask1155/gpdb,foyzur/gpdb,chrishajas/gpdb,ovr/postgres-xl,0x0FFF/gpdb,tpostgres-projects/tPostgres,rvs/gpdb,chrishajas/gpdb,kmjungersen/PostgresXL,Quikling/gpdb,rubikloud/gpdb,rvs/gpdb,xuegang/gpdb,xuegang/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,xinzweb/gpdb,edespino/gpdb,tangp3/gpdb,cjcjameson/gpdb,janebeckman/gpdb,Quikling/gpdb,yuanzhao/gpdb,zaksoup/gpdb,foyzur/gpdb,yuanzhao/gpdb,atris/gpdb,jmcatamney/gpdb,lintzc/gpdb,rubikloud/gpdb,techdragon/Postgres-XL,yuanzhao/gpdb,lpetrov-pivotal/gpdb,jmcatamney/gpdb,atris/gpdb,yazun/postgres-xl,yazun/postgres-xl,Postgres-XL/Postgres-XL,royc1/gpdb,arcivanov/postgres-xl,Quikling/gpdb,techdragon/Postgres-XL,janebeckman/gpdb,Quikling/gpdb,adam8157/gpdb,xuegang/gpdb,atris/gpdb,50wu/gpdb,xuegang/gpdb,zaksoup/gpdb,techdragon/Postgres-XL,yuanzhao/gpdb,lintzc/gpdb,oberstet/postgres-xl,adam8157/gpdb,kaknikhil/gpdb,edespino/gpdb,kaknikhil/gpdb,Chibin/gpdb,CraigHarris/gpdb,lintzc/gpdb,greenplum-db/gpdb,Chibin/gpdb,rvs/gpdb,zeroae/postgres-xl,randomtask1155/gpdb,CraigHarris/gpdb,royc1/gpdb,Chibin/gpdb,50wu/gpdb,ashwinstar/gpdb,chrishajas/gpdb,cjcjameson/gpdb,ovr/postgres-xl,0x0FFF/gpdb,janebeckman/gpdb,ashwinstar/gpdb,rubikloud/gpdb,xuegang/gpdb,greenplum-db/gpdb,lpetrov-pivotal/gpdb,tpostgres-projects/tPostgres,chrishajas/gpdb,rvs/gpdb,tpostgres-projects/tPostgres,50wu/gpdb,ahachete/gpdb,ahachete/gpdb,jmcatamney/gpdb,arcivanov/postgres-xl,zaksoup/gpdb,cjcjameson/gpdb,xuegang/gpdb,techdragon/Postgres-XL,xinzweb/gpdb,arcivanov/postgres-xl,pavanvd/postgres-xl,zeroae/postgres-xl,edespino/gpdb,rvs/gpdb,rubikloud/gpdb,zaksoup/gpdb,royc1/gpdb,edespino/gpdb,zaksoup/gpdb,ovr/postgres-xl,atris/gpdb,lintzc/gpdb,yuanzhao/gpdb,xinzweb/gpdb,tangp3/gpdb,rvs/gpdb,cjcjameson/gpdb,janebeckman/gpdb,Quikling/gpdb,rvs/gpdb,CraigHarris/gpdb,tangp3/gpdb,xinzweb/gpdb,jmcatamney/gpdb,lintzc/gpdb,randomtask1155/gpdb,chrishajas/gpdb,rubikloud/gpdb,CraigHarris/gpdb,ahachete/gpdb,lisakowen/gpdb,greenplum-db/gpdb,kaknikhil/gpdb,adam8157/gpdb,edespino/gpdb,lpetrov-pivotal/gpdb,kaknikhil/gpdb,kmjungersen/PostgresXL,zaksoup/gpdb,yuanzhao/gpdb,pavanvd/postgres-xl,0x0FFF/gpdb,yuanzhao/gpdb,lisakowen/gpdb,kaknikhil/gpdb,0x0FFF/gpdb,adam8157/gpdb,xuegang/gpdb,Postgres-XL/Postgres-XL,Chibin/gpdb,kaknikhil/gpdb,foyzur/gpdb,arcivanov/postgres-xl,Chibin/gpdb,Quikling/gpdb,postmind-net/postgres-xl,royc1/gpdb,cjcjameson/gpdb,oberstet/postgres-xl,snaga/postgres-xl,janebeckman/gpdb,xinzweb/gpdb,50wu/gpdb,janebeckman/gpdb,cjcjameson/gpdb,oberstet/postgres-xl,50wu/gpdb,royc1/gpdb,ahachete/gpdb,lintzc/gpdb,0x0FFF/gpdb,greenplum-db/gpdb,randomtask1155/gpdb,CraigHarris/gpdb,ashwinstar/gpdb,atris/gpdb,Chibin/gpdb,0x0FFF/gpdb,jmcatamney/gpdb,lisakowen/gpdb,pavanvd/postgres-xl,rubikloud/gpdb,tangp3/gpdb,lpetrov-pivotal/gpdb,lisakowen/gpdb,janebeckman/gpdb,yazun/postgres-xl,zeroae/postgres-xl,tpostgres-projects/tPostgres,pavanvd/postgres-xl,kaknikhil/gpdb,ahachete/gpdb,snaga/postgres-xl,royc1/gpdb,janebeckman/gpdb,adam8157/gpdb,oberstet/postgres-xl,kaknikhil/gpdb,lisakowen/gpdb,yuanzhao/gpdb,xinzweb/gpdb,pavanvd/postgres-xl,50wu/gpdb,foyzur/gpdb,ahachete/gpdb,kaknikhil/gpdb,zeroae/postgres-xl,ashwinstar/gpdb,Chibin/gpdb,edespino/gpdb,tangp3/gpdb,randomtask1155/gpdb,50wu/gpdb,adam8157/gpdb,postmind-net/postgres-xl,50wu/gpdb,ashwinstar/gpdb,oberstet/postgres-xl,ovr/postgres-xl,cjcjameson/gpdb,lpetrov-pivotal/gpdb,postmind-net/postgres-xl,zaksoup/gpdb,kmjungersen/PostgresXL,randomtask1155/gpdb,kaknikhil/gpdb,Quikling/gpdb,lintzc/gpdb,postmind-net/postgres-xl,arcivanov/postgres-xl,snaga/postgres-xl,0x0FFF/gpdb,zaksoup/gpdb,lintzc/gpdb,edespino/gpdb,cjcjameson/gpdb,lpetrov-pivotal/gpdb,ahachete/gpdb,chrishajas/gpdb,xinzweb/gpdb