MT#61856 docs: remove duplicated intro from index

Remove the intro information from index,
because already mentioned in the overview.

Also change a greeting title.

Change-Id: I5c232fa033eac8e3097ad5adb351e8940a33a4ee
(cherry picked from commit a07b972000)

docs/index.rst

@@ -2,13 +2,8 @@
 .. _Sipwise: https://www.sipwise.com
 .. _Kamailio: https://www.kamailio.org/
 
-What is rtpengine?
-=====================================
-
-The `Sipwise`_ NGCP rtpengine is a proxy for RTP traffic and other UDP based media traffic.
-It's meant to be used with the `Kamailio`_ SIP proxy and forms a drop-in replacement for any of the other available RTP and media proxies.
-
-Currently the only supported platform is GNU/Linux.
+Welcome to the Rtpengine Project Documentation
+==============================================
 
 .. toctree::
    :maxdepth: 4