Fix p tag in UnicodeDoS.qhelp

Author: Sim4n6

python/ql/src/experimental/Security/CWE-770/UnicodeDoS.qhelp

@@ -6,7 +6,7 @@
 <overview>
 <p>When a remote user-controlled data can reach a costly Unicode normalization with either form, NFKC or NFKD, an attack such as the One Million Unicode Characters, could lead to a denial of service on Windows OS.</p> 
 
-<p>And, with the use of special Unicode characters, like U+2100 (℀) or U+2105 (℅), the payload size could be tripled after the compatibility normalization.
+<p>And, with the use of special Unicode characters, like U+2100 (℀) or U+2105 (℅), the payload size could be tripled after the compatibility normalization.</p>
 
 </overview>
 <recommendation>