Fix typo in the documentation

jwilk · jwilk · commit 290fe7563feb · 2015-12-14T13:30:19.000+01:00
diff --git a/docs/rulesets.html b/docs/rulesets.html
@@ -129,7 +129,7 @@ <h4>
   href="http://www.regular-expressions.info/pcre.html">Perl-style regular
   expressions.</a>
   Note that if your rules include ampersands (&amp;), they need
-  to be appropriately XML-encoded: replace each occurence of
+  to be appropriately XML-encoded: replace each occurrence of
   <strong>&amp;</strong> with <strong>&amp;#x26;</strong>.
 </p>
 
