[PATCH 3 of 3 STABLE V2] doc: add explanation about Mercurial specific escaping for subpaths

[FUJIWARA Katsunori]

# HG changeset patch
# User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
# Date 1337155350 -32400
# Branch stable
# Node ID 7cd7ea68a04d5f28d664f6183a3e07011b1a89a0
# Parent  c3eeae0a2e0ff4c0f493eb918f7458f2b12d93cb
doc: add explanation about Mercurial specific escaping for subpaths

diff -r c3eeae0a2e0f -r 7cd7ea68a04d mercurial/help/config.txt
--- a/mercurial/help/config.txt	Wed May 16 17:02:30 2012 +0900
+++ b/mercurial/help/config.txt	Wed May 16 17:02:30 2012 +0900
@@ -1065,6 +1065,16 @@
 
 rewrites ``http://server/foo-hg/`` into ``http://hg.server/foo/``.
 
+.. note:: Even on Windows platforms, it is recommended to use ``/`` as
+   the path delimiter for local paths instead of ``\``, because the latter is
+   the special character for the regular expression.
+
+   For convenience, recent Mercurial escapes backslashes in
+   ``replacement`` at first, and then treats backslashes followed by
+   digits as back references of the regular expression. So, you can not
+   specify "the path element starting with digits" with backslashes as
+   path delimiters in ``replacement``.
+
 Relative subrepository paths are first made absolute, and the the
 rewrite rules are then applied on the full (absolute) path. The rules
 are applied in definition order.