backport r1379311: Add a notion that, for a skip flag to be used, the rewrite...

<section id="flag_s"><title>S|skip</title>

<p>The [S] flag is used to skip rules that you don't want to run. The 

syntax of the skip flag is [S=<em>N</em>], where <em>N</em> signifies 

the number of rules to skip. This can be thought of as a <code>goto</code> 

the number of rules to skip (provided the <directive module="mod_rewrite">

RewriteRule</directive> matches). This can be thought of as a <code>goto</code> 

statement in your rewrite ruleset. In the following example, we only want 

to run the <directive module="mod_rewrite">RewriteRule</directive> if the 

requested URI doesn't correspond with an actual file.</p>