[xmppclient] Improved readme file (#5722)
[xmppclient] Improved readme file (#5722)

* Improved readme

Signed-off-by: Pavel Gololobov <2375fa63e2908bb2df59f606483a3aa92321db7a@ochat.org>
Snickermicker/openhab2,Snickermicker/openhab2,theoweiss/openhab2,theoweiss/openhab2,Snickermicker/openhab2,theoweiss/openhab2,Snickermicker/openhab2,theoweiss/openhab2