frr: update README

* Clarify that FRR implements as well as manages protocols
* Move IS-IS out of "early support"
* Add Babel - friends don't leave friends out of READMEs!
* Add mention of further information

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

README

@@ -1,9 +1,9 @@
-FRRouting is free software that manages various IPv4 and IPv6 routing
-protocols.
+FRRouting is free software that implements and manages various IPv4 and IPv6
+routing protocols.
 
-Currently FRRouting supports BGP4, BGP4+, OSPFv2, OSPFv3, RIPv1,
-RIPv2, RIPng, PIM-SM/MSDP and LDP as well as very early support for IS-IS,
-EIGRP and NHRP.
+Currently FRRouting supports BGP4, BGP4+, OSPFv2, OSPFv3, RIPv1, RIPv2, RIPng,
+IS-IS, PIM-SM/MSDP, LDP and Babel as well as very early support for EIGRP and
+NHRP.
 
 See the file REPORTING-BUGS to report bugs.
 
@@ -12,3 +12,5 @@ Free RRRouting is free software. See the file COPYING for copying conditions.
 Public email discussion can be found at https://lists.frrouting.org/listinfo
 
 Our public slack channel is at https://frrouting.slack.com
+
+For information on contributing, please see COMMUNITY.md