[PATCH 2 of 2] help: deprecate ui.slash in favor of slashpath template filter (issue5572)

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1508574434 -32400
#      Sat Oct 21 17:27:14 2017 +0900
# Node ID 740dce20be8f125bd7a55aad849932e1c40820a9
# Parent  c2ff7689990d5c163cff48c38880928ee98e4248
help: deprecate ui.slash in favor of slashpath template filter (issue5572)

> For some reason, I thought someone (Mads?) said we had basically given
> up on ui.slash, and some commands didn't support it.
(from https://bz.mercurial-scm.org/show_bug.cgi?id=5572#c1)

So the ui.slash option doesn't always work and is somewhat confusing. Let's
make it clearer we won't improve the situation.

diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -2184,6 +2184,8 @@ User interface controls.
     (default: True)
 
 ``slash``
+    (Deprecated. Use ``slashpath`` template filter instead.)
+
     Display paths using a slash (``/``) as the path separator. This
     only makes a difference on systems where the default path
     separator is not the slash character (e.g. Windows uses the