Correct mention that a full backup is needed after database creation

Michael Paquier · Michael Paquier · commit 05601aa8f68d · 2016-01-19T13:01:40.000+09:00
This restriction has been inherited from the upstream project pg_rman, however
the new differential facility is proving to be able to address that need quite
nicely after more testing regarding that.

Mentioned by Thomas Reiss.
diff --git a/doc/pg_arman.txt b/doc/pg_arman.txt
@@ -343,8 +343,6 @@ pg_arman has the following restrictions.
 - If there are some unreadable files/directories in data folder of server
   WAL directory or archived WAL directory, the backup or restore will fail
   depending on the backup mode selected.
-- Differential backup is not able to take necessary files after a database
-  creation, so take a full backup once a new database is created.
 
 == DETAILS ==
 
