Reorganize documentation index

Moved examples and use cases into a common subdir so those topics will
get grouped together in the main sidebar/TOC

doc/examples/httpmonitor/http_proxy_02.bro

@@ -0,0 +1,26 @@
+
+module HTTP;
+
+export {
+
+	global success_status_codes: set[count] = {
+		200,
+		201,
+		202,
+		203,
+		204,
+		205,
+		206,
+		207,
+		208,
+		226,
+		304
+	};
+}
+
+event http_reply(c: connection, version: string, code: count, reason: string)
+	{
+	if ( /^[hH][tT][tT][pP]:/ in c$http$uri &&
+	     c$http$status_code in HTTP::success_status_codes )
+		print fmt("A local server is acting as an open proxy: %s", c$id$resp_h);
+	}