Update README

Author: hcarty

README.md

@@ -1,8 +1,12 @@
 # ezgzip - Simple gzip (de)compression library
 
+ezgzip is a simple interface focused on `string -> string` zlib and gzip
+(de)compression.
+
 Documentation is available
 [here](https://hcarty.github.io/ezgzip/ezgzip/index.html).
 
+An example illustrating how to gzip compress and then decompress a string:
 ```ocaml
 open Rresult
 
@@ -13,6 +17,11 @@ let () =
   assert (original = decompressed)
 ```
 
+This library currently uses the zlib bindings provided by
+[camlzip](https://github.com/xavierleroy/camlzip).  The gzip header/footer code
+is based on the
+[upstream specification](http://www.gzip.org/zlib/rfc-gzip.html#specification).
+
 ## Compile
 
 ```