doc: added README

Author: tokers

README.md

@@ -1,2 +1,109 @@
-# zstd-nginx-module
-Nginx module for the Zstandard compression
+# Name
+zstd-nginx-module - Nginx module for the [Zstandard compression](https://facebook.github.io/zstd/).
+
+# Table of Content
+
+* [Name](#name)
+* [Status](#status)
+* [Synopsis](#synopsis)
+* [Installation](#installation)
+* [Directives](#directives)
+  * [zstd_dict_file](#zstd_dict_file)
+  * [zstd](#zstd)
+  * [zstd_comp_level](#zstd_comp_level)
+  * [zstd_min_length](#zstd_min_length)
+  * [zstd_types](#zstd_types)
+  * [zstd_buffers](#zstd_buffers)
+* [Author](#author)
+
+# Status
+
+This Nginx module is currently considered experimental. Issues and PRs are welcome if you encounter any problems.
+
+# Synopsis
+
+```nginx.conf
+
+# specify the dictionary
+zstd_dict_file /path/to/dict;
+
+server {
+    listen 127.0.0.1:8080;
+    server_name localhost;
+
+    location / {
+        # enable zstd compression
+        zstd on;
+        zstd_min_length 256; # no less than 256 bytes
+        zstd_comp_level 3; # set the level to 3
+
+        proxy_pass http://foo.com;
+    }
+}
+```
+
+# Installation
+
+To use this module, configure your nginx branch with `--add-module=/path/to/zstd-nginx-module`. several points should be taken care.
+
+* You can environment variables `ZSTD_INC` and `ZSTD_LIB` to specify the path to `zstd.h` and the path to zstd shared library represently.
+* static library is tried prior to dynamic library, since this Nginx module uses some **advanced APIs** where static linking is recommended.
+* System zstd bundle will be tries if `ZSTD_INC` and `ZSTD_LIB` are not specified.
+
+# Directives
+
+## zstd_dict_file
+
+**Syntax:** *zstd_dict_file /path/to/dict;*  
+**Default:** *-*  
+**Context:** *http*  
+
+Specifies the external dictionary.
+
+## zstd
+
+**Syntax:** *zstd on | off;*  
+**Default:** *zstd off;*  
+**Context:** *http, server, location, if in location*
+
+Enables or disables zstd compression for response.
+
+## zstd_comp_level
+
+**Syntax:** *zstd_comp_level level;*  
+**Default:** *zstd_comp_level 1;*  
+**Context:** *http, server, location*
+
+Sets a zstd compression level of a response. Acceptable values are in the range from 1 to `ZSTD_maxCLevel()`.
+
+## zstd_min_length
+
+**Syntax:** *zstd_min_length length;*  
+**Default:** *zstd_min_length 20;*  
+**Context:** *http, server, location*
+
+Sets the minimum length of a response that will be compressed by zstd. The length is determined only from the "Content-Length" response header field.
+
+## zstd_types
+
+**Syntax:** *zstd_types mime-type ...;*  
+**Default:** *zstd_types text/html;*  
+**Context:** *http, server, location*
+
+Enables ztd of responses for the specified MIME types in addition to "text/html". The special value "*" matches any MIME type.
+
+## zstd_buffers
+
+**Syntax:** *zstd_buffers number size;*  
+**Default:** *zstd_buffers 32 4k | 16 8k;*  
+**Context:** *http, server, location*
+
+Sets the number and size of buffers used to compress a response. By default, the buffer size is equal to one memory page. This is either 4K or 8K, depending on a platform.
+
+# Author
+
+Alex Zhang (张超) zchao1995@gmail, UPYUN Inc.
+
+# License
+
+This Nginx module is licensed under [BSD 2-Clause License](LICENSE).