Add a README that explains how Append-Only Tables work.
Add a README that explains how Append-Only Tables work.

rvs/gpdb,xuegang/gpdb,xuegang/gpdb,edespino/gpdb,janebeckman/gpdb,xuegang/gpdb,ashwinstar/gpdb,kaknikhil/gpdb,adam8157/gpdb,50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,xinzweb/gpdb,janebeckman/gpdb,Chibin/gpdb,Quikling/gpdb,Chibin/gpdb,adam8157/gpdb,edespino/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,lintzc/gpdb,Chibin/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,lintzc/gpdb,yuanzhao/gpdb,xinzweb/gpdb,janebeckman/gpdb,rvs/gpdb,xuegang/gpdb,xuegang/gpdb,CraigHarris/gpdb,Chibin/gpdb,jmcatamney/gpdb,kaknikhil/gpdb,janebeckman/gpdb,rvs/gpdb,kaknikhil/gpdb,lintzc/gpdb,ashwinstar/gpdb,lisakowen/gpdb,adam8157/gpdb,janebeckman/gpdb,edespino/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,Chibin/gpdb,janebeckman/gpdb,lisakowen/gpdb,ashwinstar/gpdb,yuanzhao/gpdb,edespino/gpdb,edespino/gpdb,adam8157/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,Chibin/gpdb,xinzweb/gpdb,cjcjameson/gpdb,lisakowen/gpdb,rvs/gpdb,lintzc/gpdb,50wu/gpdb,xinzweb/gpdb,jmcatamney/gpdb,janebeckman/gpdb,50wu/gpdb,CraigHarris/gpdb,xinzweb/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,lintzc/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,yuanzhao/gpdb,edespino/gpdb,Quikling/gpdb,edespino/gpdb,lisakowen/gpdb,xuegang/gpdb,yuanzhao/gpdb,Chibin/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,yuanzhao/gpdb,kaknikhil/gpdb,50wu/gpdb,cjcjameson/gpdb,CraigHarris/gpdb,ashwinstar/gpdb,adam8157/gpdb,Quikling/gpdb,rvs/gpdb,edespino/gpdb,cjcjameson/gpdb,lisakowen/gpdb,lintzc/gpdb,edespino/gpdb,50wu/gpdb,greenplum-db/gpdb,cjcjameson/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,CraigHarris/gpdb,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,kaknikhil/gpdb,CraigHarris/gpdb,rvs/gpdb,Quikling/gpdb,rvs/gpdb,adam8157/gpdb,kaknikhil/gpdb,jmcatamney/gpdb,janebeckman/gpdb,lintzc/gpdb,lisakowen/gpdb,ashwinstar/gpdb,greenplum-db/gpdb,xuegang/gpdb,yuanzhao/gpdb,Chibin/gpdb,lisakowen/gpdb,kaknikhil/gpdb,Chibin/gpdb,cjcjameson/gpdb,xuegang/gpdb,50wu/gpdb,adam8157/gpdb,CraigHarris/gpdb,Quikling/gpdb,lintzc/gpdb,rvs/gpdb,xuegang/gpdb,Quikling/gpdb,cjcjameson/gpdb,adam8157/gpdb,janebeckman/gpdb,50wu/gpdb,50wu/gpdb,janebeckman/gpdb,edespino/gpdb,jmcatamney/gpdb,Quikling/gpdb,rvs/gpdb,jmcatamney/gpdb,xinzweb/gpdb,jmcatamney/gpdb,Quikling/gpdb,Chibin/gpdb,CraigHarris/gpdb,Quikling/gpdb,cjcjameson/gpdb,rvs/gpdb,cjcjameson/gpdb,cjcjameson/gpdb,Quikling/gpdb,lintzc/gpdb,kaknikhil/gpdb,jmcatamney/gpdb