[PATCH 3 of 5] rebase: simplify documentation about --keep

[timeless]

# HG changeset patch
# User timeless <timeless at mozdev.org>
# Date 1450462923 0
#      Fri Dec 18 18:22:03 2015 +0000
# Node ID 9a97dd525927e7b2422d2e0975f394a01baee245
# Parent  600dd16bf6f8321d77afb1eda8b4aaf2a1e477cc
rebase: simplify documentation about --keep

Also include a warning about bookmarks

diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -128,11 +128,11 @@
       3. Use ``--base`` to select a changeset; rebase will find ancestors
       and their descendants which are not also ancestors of the destination.
 
-    By default, rebase recreates the changesets in the source branch
-    as descendants of dest and then destroys the originals. Use
-    ``--keep`` to preserve the original source changesets. Some
-    changesets in the source branch (e.g. merges from the destination
-    branch) may be dropped if they no longer contribute any change.
+    Rebase will destroy original changesets unless you use ``--keep``.
+    It will also move your bookmarks (even if you do).
+
+    Some changesets may be dropped if they do not contribute changes
+    (e.g. merges from the destination branch).
 
     One result of the rules for selecting the destination changeset
     and source branch is that, unlike ``merge``, rebase will do