Update README.md

README.md

@@ -4,4 +4,56 @@
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-This package is a library of ZKits.
+## About ##
+
+This package is a library of ZKits project. 
+This library provides the function of managing the runtime environment for the application. 
+Generally, no additional work is needed to realize the type of runtime environment shared 
+between the various components of the application.
+
+## Usage ##
+1. Import package.
+   ```sh
+   go get -u -v github.com/edoger/zkits-environment
+   ```
+2. Example.
+   ```go
+   package main
+   
+   import (
+       "flag"
+   
+       "github.com/edoger/zkits-environment"
+   )
+   
+   func main() {
+       var env string
+       flag.StringVar(&env, "env", "", "The runtime environment")
+       flag.Parse()
+   
+       // Set the runtime environment value.
+       // If the given runtime environment is not registered, an error is returned.
+       err := environment.Set(environment.Env(env))
+       if err != nil {
+           // Handle error.
+       }
+   
+       // Get the current runtime environment.
+       // If it has never been set, then you get the environment.Development by default.
+       environment.Get()
+   
+       // Not enough built-in runtime environment?
+       // Register functions can register any custom runtime environment.
+       // Note: Registration must be before setup.
+       environment.Register("foo")
+   }
+   ```
+3. These are the runtime environments that are already built in and registered.
+   ```
+   environment.Development  // "development"
+   environment.Testing      // "testing"
+   environment.Prerelease   // "prerelease"
+   environment.Production   // "production"
+   ```
+## License ##
+[Apache-2.0](http://www.apache.org/licenses/LICENSE-2.0)