Fix #74599: parse_url allows bad characters in the common name

We remove this sentence altogether, because the return values section
provides the correct info now (besides that "invalid" is not specific
enough, the replacement is done on the result, not on the input).

reference/url/functions/parse-url.xml

@@ -34,8 +34,7 @@
      <term><parameter>url</parameter></term>
      <listitem>
       <para>
-       The URL to parse. Invalid characters are replaced by
-       <literal>_</literal>.
+       The URL to parse.
       </para>
      </listitem>
     </varlistentry>