Slightly modify the "publish" command description

Signed-off-by: Catalin Marinas <catalin.marinas@gmail.com>

stgit/commands/publish.py

diff --git a/stgit/commands/publish.py b/stgit/commands/publish.py
index 71b8118..391a6a2 100644
--- a/stgit/commands/publish.py
+++ b/stgit/commands/publish.py
@@ -23,7 +23,7 @@
 from stgit.out import out
 from stgit import utils
 
-help = 'Publish the stack changes to a merge-friendly head'
+help = 'Push the stack changes to a merge-friendly branch'
 kind = 'stack'
 usage = ['[options] [branch]']
 description = """