[PATCH] help: add verb to sentence in phases.txt

[Johan Samyn]

# HG changeset patch
# User Johan Samyn <johan.samyn at gmail.com>
# Date 1331554948 -3600
# Node ID c725d6e052b7da6494fa0022720802e4c1464023
# Parent  60cc3a0d224972e0fca00fe93f0488b5e4a60c7c
help: add verb to sentence in phases.txt

diff --git a/mercurial/help/phases.txt b/mercurial/help/phases.txt
--- a/mercurial/help/phases.txt
+++ b/mercurial/help/phases.txt
@@ -14,7 +14,7 @@
 These phases are ordered (public < draft < secret) and no changeset
 can be in a lower phase than its ancestors. For instance, if a
 changeset is public, all its ancestors are also public. Lastly,
-changeset phases only be changed towards the public phase.
+changeset phases should only be changed towards the public phase.
 
 How are phases managed?
 -----------------------