add: files for improve github community rating

README.md

@@ -35,5 +35,9 @@ func handle(w http.ResponseWriter, r *http.Request) {
 ## sample image
 ![image](example/captcha.png)
 
+## Contributing
+If your found a bug, please contribute!
+see [contributing.md](contributing.md) for more detail
+
 ## License
 [MIT](LICENSE.md)

code-of-conduct.md

@@ -0,0 +1 @@
+[https://contributor-covenant.org/version/1/4/](https://contributor-covenant.org/version/1/4/)

contributing.md

@@ -0,0 +1,17 @@
+First off, thank you for considering contributing to captcha. It's people like you that make captcha such a great module.
+
+Following these guidelines helps to communicate that you respect the time of the developers managing and developing this open source project. In return, they should reciprocate that respect in addressing your issue, assessing changes, and helping you finalize your pull requests.
+
+Captcha is an open source project and we love to receive contributions from our community — you! There are many ways to contribute, from writing blog posts, improving the documentation, submitting bug reports and feature requests or writing code which can be incorporated into captcha itself.
+
+Step your can follow to start:
+1. Fork it!
+2. Create your feature branch: `git checkout -b my-new-feature`
+3. Commit your changes: `git commit -am 'Add some feature'`
+4. Push to the branch: `git push origin my-new-feature`
+5. Submit a pull request :D
+
+Ground Rules:
+- Ensure all tests pass.
+- Run `go fmt` before commit. Event better, make go report happy. 
+- Make sure you only implement ONE feature or bugfix in a pull request. Do not split one line fix in multiple commits to confuse others either.

history.md

@@ -0,0 +1,4 @@
+0.9.0 / 2017-09-20
+===================
+
+* Initial release