update README.md

Author: bicycle1885

README.md

@@ -1,7 +1,40 @@
-# TranscodingStreams
+TranscodingStreams.jl - IO streams with transcoding
+===================================================
 
-[![Build Status](https://travis-ci.org/bicycle1885/TranscodingStreams.jl.svg?branch=master)](https://travis-ci.org/bicycle1885/TranscodingStreams.jl)
+<!--[![Docs Latest][docs-latest-img]][docs-latest-url]-->
+[![TravisCI Status][travisci-img]][travisci-url]
+<!--[![Appveyor Status][appveyor-img]][appveyor-url]-->
+[![codecov.io][codecov-img]][codecov-url]
 
-[![Coverage Status](https://coveralls.io/repos/bicycle1885/TranscodingStreams.jl/badge.svg?branch=master&service=github)](https://coveralls.io/github/bicycle1885/TranscodingStreams.jl?branch=master)
+TranscodingStreams.jl exports a type `TranscodingStream{C<:Codec,S<:IO}<:IO`
+which wraps `S<:IO` using `C<:Codec`. Codecs are exported from other packages
+listed below:
 
-[![codecov.io](http://codecov.io/github/bicycle1885/TranscodingStreams.jl/coverage.svg?branch=master)](http://codecov.io/github/bicycle1885/TranscodingStreams.jl?branch=master)
+- [CodecZlib.jl](https://github.com/bicycle1885/CodecZlib.jl)
+    - `GzipCompression` (`GzipCompressionStream`)
+    - `GzipDecompression` (`GzipDecompressionStream`)
+    - `ZlibCompression` (`ZlibCompressionStream`)
+    - `ZlibDecompression` (`ZlibDecompressionStream`)
+    - `RawCompression` (`RawCompressionStream`)
+    - `RawDecompression` (`RawDecompressionStream`)
+- [CodecZstd.jl](https://github.com/bicycle1885/CodecZstd.jl)
+    - `ZstdCompression` (`ZstdCompressionStream`)
+    - `ZstdDecompression` (`ZstdDecompressionStream`)
+
+The following snippet is an example of using CodecZlib.jl, which exports
+`GzipDecompressionStream` as an alias of
+`TranscodingStream{GzipDecompression,S}` where `S<:IO`:
+
+```julia
+using CodecZlib
+stream = GzipDecompressionStream(open("data.gzip"))
+for line in eachline(stream)
+    # do something...
+end
+close(stream)
+```
+
+[travisci-img]: https://travis-ci.org/bicycle1885/TranscodingStreams.jl.svg?branch=master
+[travisci-url]: https://travis-ci.org/bicycle1885/TranscodingStreams.jl
+[codecov-img]: http://codecov.io/github/bicycle1885/TranscodingStreams.jl/coverage.svg?branch=master
+[codecov-url]: http://codecov.io/github/bicycle1885/TranscodingStreams.jl?branch=master