Mention that we're aiming to follow RFC 7159 now.

Cause README.md to show up in Doxygen output as the main page.

README.md

@@ -1,6 +1,14 @@
-`json-c`
+`json-c`                       {#mainpage}
 ========
 
+JSON-C - A JSON implementation in C
+-----------------------------------
+
+JSON-C implements a reference counting object model that allows you to easily 
+construct JSON objects in C, output them as JSON formatted strings and parse 
+JSON formatted strings back into the C representation of JSON objects.
+It aims to conform to <a href="https://tools.ietf.org/html/rfc7159">RFC 7159</a>
+
 Building on Unix with `git`, `gcc` and `autotools`
 --------------------------------------------------