utils: added remarks section with note about libcurl leak on centos 6

- based on GH #853

modules/utils/doc/utils_admin.xml

@@ -415,4 +415,15 @@ id switch                         filter proxy
 			<listitem>digit               ::= ? 0-9 ?</listitem>
 		</itemizedlist>
 	</section>
+	<section id="utils.s.remarks">
+		<title>Remarks</title>
+		<para>
+			Note: libcurl leak in CentOS 6 - this module uses libcurl library
+			and in case if you are using CentOS 6, be aware that standard
+			libcurl-7.19.7-52 has a memory leak. To fix this memory, install
+			libcurl from city-fan repository. More details at:
+			<ulink url="https://www.digitalocean.com/community/questions/how-to-upgrade-curl-in-centos6">
+				https://www.digitalocean.com/community/questions/how-to-upgrade-curl-in-centos6</ulink>
+		</para>
+	</section>
 </chapter>