[master] 32dbbfbdb release docs: better motivation for std.fnmatch()

[Nils Goroll]

commit 32dbbfbdb5447380de9075214a8b795944c11e79
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Sep 10 19:43:10 2018 +0200

    release docs: better motivation for std.fnmatch()

diff --git a/doc/sphinx/whats-new/upgrading-6.1.rst b/doc/sphinx/whats-new/upgrading-6.1.rst
index df71404f1..428a764ae 100644
--- a/doc/sphinx/whats-new/upgrading-6.1.rst
+++ b/doc/sphinx/whats-new/upgrading-6.1.rst
@@ -135,8 +135,11 @@ VMODs
 =====
 
 Added the :ref:`func_fnmatch` function to :ref:`vmod_std(3)`, which
-you can use for shell-style wildcard matching (if you prefer that to
-regular expressions).
+you can use for shell-style wildcard matching. :ref:`func_fnmatch` can
+be more efficient than regular expressions, in particular in cases
+where the pattern is dynamically defined.
+
+.. should we mention vmod_re for dynamic regexen?
 
 :ref:`vmod_unix(3)` is now supported for SunOS and descendants. This
 entails changing the privilege set of the child process while the VMOD