Add missing QHelp files

python/ql/src/Lexical/CommentedOutCodeMetricOverview.qhelp

@@ -0,0 +1,12 @@
+<!DOCTYPE qhelp PUBLIC
+  "-//Semmle//qhelp//EN"
+  "qhelp.dtd">
+<qhelp>
+<overview>
+<p>
+This metric counts the number of lines of commented-out code in each file. Large amounts of
+commented-out code often indicate poorly maintained code.
+</p>
+
+</overview>
+</qhelp>