Add "Constant" column to error code table.
Add "Constant" column to error code table.

Also, better mark section headings.

kdio@uenf.br

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