fix typo on db.getReplicationinfo

Author: jeff-allen-mongo

source/reference/method/db.getReplicationInfo.txt

@@ -78,7 +78,7 @@ Output
 
 .. data:: db.getReplicationInfo.now
 
-   Returns a time stamp that reflects reflecting the current time.
+   Returns a timestamp that reflects the current time.
    The shell process generates this value, and the datum may differ
    slightly from the server time if you're connecting from a remote host
    as a result. Equivalent to :method:`Date()`.