Fix xml syntax in token-matching.xml (#2197)

The file token-matching.xml contains multiple rules
- Add <rules></rules> xml tags
- Fixes the following xmllint error:
  ./rules/token-matching.xml:10: parser error :
  Extra content at the end of the document
  <rule version="1">
  ^

rules/token-matching.xml

@@ -1,4 +1,5 @@
 <?xml version="1.0"?>
+<rules>
     <rule version="1">
         <pattern>Token :: (?:findm|(?:simple|)M)atch \([^,]+,\s+"(?:\s+|[^"]+?\s+")</pattern>
         <message>
@@ -32,3 +33,4 @@ without special pattern requirements.</summary>
             <summary>tok->strAt(0) is a slow way to say tok->str()</summary>
         </message>
     </rule>
+</rules>