Add readme for XMPP check domain

cmd/xmpp-check/README.md

@@ -0,0 +1,28 @@
+# XMPP Check
+
+XMPP check is a tool to check TLS certificate on a remote server.
+
+## Installation
+
+```
+$ go get -u gosrc.io/xmpp/cmd/xmpp-check
+```
+
+## Usage
+
+If you server is on standard port and XMPP domains matches the hostname you can simply use:
+
+```
+$ xmpp-check myhost.net:5222 xmppdomain.net
+2019/05/16 16:04:36 All checks passed
+```
+
+You can also pass the port and the XMPP domain if different from the server hostname:
+
+```
+$ xmpp-check myhost.net:5222 xmppdomain.net
+2019/05/16 16:04:36 All checks passed
+```
+
+Error code will be non-zero in case of error. You can thus use it directly with your usual 
+monitoring scripts.