A typo in backend/replication/README

Hi, I found a trivial typo in backend/replication/README

| Walreceiver IPC
| ---------------
| 
| When the WAL replay in startup process has reached the end of archived WAL,
| recoverable using recovery_command, it starts up the walreceiver process

I think the recovery_command should be restore_command. This was
introduced at 9.0dev and all of REL9_x_STABLE contain this. I
don't know how "recoverable using restore_command" looks wired,
but I changed the sentsnce to fit the parameter name.

Likewise, the release note for 8.3.2 at HEAD@master contains the
similar typo. The typo originates in 8.4dev and back patched to
8.3.2 but I suspect that the all branches originates from 8.4dev
need to be fixed.

Patch 1: Fix for replication/README@@master
Patch 2: Fix for release-8.3.sgml@master

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center