doc/mgr: edit localpool.rst

Remove "only" where it was extraneous.

This commit was made in response to a request made by Anthony D'Atri
here: ceph#63419 (comment).

Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/mgr/localpool.rst

@@ -34,8 +34,8 @@ The ``localpool`` module understands the following options:
 
 The default is ``by-$subtreetype-``.
 
-These options are set via the ``config-key`` interface. For example, to
-change the replication level to 2x with only 64 PGs, run the following two commands:
+These options are set via the ``config-key`` interface. For example, to change
+the replication level to 2x with 64 PGs, run the following two commands:
 
 .. prompt:: bash #