[doc] add C++ to the README

Summary: Duh!

Reviewed By: dulmarod

Differential Revision: D7443714

fbshipit-source-id: 319aa5c

README.md

@@ -1,7 +1,7 @@
 # Infer [![Build Status](https://travis-ci.org/facebook/infer.svg?branch=master)](https://travis-ci.org/facebook/infer)
 
 [Infer](http://fbinfer.com/) is a static analysis tool for Java,
-Objective-C and C, written in [OCaml](https://ocaml.org/).
+C++, Objective-C, and C. Infer is written in [OCaml](https://ocaml.org/).
 
 
 ## Installation