Extend the intro a bit

Author: bbatsov

README.md

@@ -15,7 +15,8 @@ CIDER extends Emacs with support for interactive programming in Clojure. The
 features are centered around `cider-mode`, an Emacs minor-mode that complements
 `clojure-mode`. While `clojure-mode` supports editing Clojure source files,
 `cider-mode` adds support for interacting with a running Clojure process for
-compilation, debugging, documentation lookup, and so on.
+compilation, debugging, definition and documentation lookup, running tests and
+so on.
 
 CIDER is the successor to the now deprecated combination of using [SLIME][] +
 [swank-clojure][] for Clojure development.