Implement readme improvements proposed in #13 and #15.

README.md

@@ -1,7 +1,8 @@
 # Python A2S
 
-Library to query Source and GoldSource servers. Rewrite of the
-[python-valve](https://github.com/serverstf/python-valve) module.
+Library to query Source and GoldSource servers.
+Impliments [Valve's Server Query Protocol](https://developer.valvesoftware.com/wiki/Server_queries).
+Rewrite of the [python-valve](https://github.com/serverstf/python-valve) module.
 Supports both synchronous and asyncronous applications.
 
 Official demo application: [Sourcequery](https://sourcequery.yepoleb.at)
@@ -43,8 +44,10 @@ All functions also have an async version as of package 1.2.0 that adds an `a` pr
 
 * `a2s.BrokenMessageError(Exception)` - General decoding error
 * `a2s.BufferExhaustedError(BrokenMessageError)` - Response too short
-* `socket.timeout` - No response
+* `socket.timeout` - No response (synchronous calls)
+* `asyncio.exceptions.TimeoutError` - No response (async calls)
 * `socket.gaierror` - Address resolution error
+* `ConnectionRefusedError` - Target port closed
 
 ## Examples