Ruby: fix typo in qhelp

Author: hmac

ruby/ql/src/queries/security/cwe-502/UnsafeDeserialization.qhelp

@@ -23,7 +23,7 @@ If deserializing an untrusted YAML document using the <code>psych</code> gem,
 prefer the <code>safe_load</code> and <code>safe_load_file</code> methods over
 <code>load</code> and <code>load_file</code>, as the former will safely
 handle untrusted data. Avoid passing untrusted data to the <code>load_stream</code>
-method. In <code>psych</code> version 4.0.0 and above, the <code>load</code> can
+method. In <code>psych</code> version 4.0.0 and above, the <code>load</code> method can
 safely be used.
 </p>