add install notes to README

README.md

@@ -3,8 +3,8 @@ SMTP to HTTP gateway
 
 Usage
 -----
-Begin listening for incoming messages over SMTP and post them to the sepcified
-HTTP endpoint.
+Begin listening for incoming SMTP messages, parse them, and post them to the
+specified HTTP endpoint.
 ```sh
 smtp2http https://dev-services.zingle.me/inbound-communication/email
 ```
@@ -17,3 +17,10 @@ CA=/etc/private/ssl/zingle-ca.crt
 smtp2http -T$CERT:$KEY:$CA https://dev-services.zingle.me/foo
 ```
 
+Install
+-------
+```sh
+git clone git@github.com:Zingle/smtp2http.git
+cd smtp2http
+npm install -g
+```sh