Update SquidClientTool.md

Author: kinkie

docs/Features/CacheManager/SquidClientTool.md

@@ -2,10 +2,25 @@
 
 This tool is a command line utility for performing web requests.
 
-It also has a special ability to send cache manager requests to Squid
+It also has the ability to send cache manager requests to Squid
 proxies.
 
+:warning: The `squidclient` tool is no longer distributed with
+Squid 7 and later. Squid-4 and later offer access to the cache
+manager over HTTP, which can be accessed using any web browser
+or command line tools such as `curl`
+
+To access it:
+`curl -u user:pass http://127.0.0.1:3128/squid-internal-mgr/menu`
+(`user` can be any, `pass` is the password set with `cachemgr_passwd` in `squid.conf`.)
+
+Replace `menu` with the cache manager report you are interested in,
+and 127.0.0.1 with host running squid. Make sure that the cache's `http_access`
+rules grant access to the cache itself.
+
+
 ## Cache manager access from squidclient
+:warning: this section is for historic reference only.
 
 A simple way to test the access to the cache manager is:
 ```