Add README for sip_client

Author: dpocock

examples/sip_client/README.txt

@@ -0,0 +1,22 @@
+
+
+Checkout the project from git
+
+At the top level, run cmake:
+
+  cmake -G 'Unix Makefiles' \
+     -D BUILD_EXAMPLES=ON \
+     -D WEBSOCKETPP_ROOT=/tmp/cm1 \
+     -D ENABLE_CPP11=OFF .
+
+and then make the example:
+
+  make -C examples/sip_client
+
+Now run it:
+
+  bin/sip_client ws://ws-server:80
+
+It has been tested against the repro SIP proxy from reSIProcate
+
+  http://www.resiprocate.org/WebRTC_and_SIP_Over_WebSockets