Merge pull request #3 from gilteunchoi/add-readme

Add README

Author: youknowone

README.md

@@ -27,6 +27,16 @@ or using docker
     __doc__  RustPython
     $ docker run -v $(pwd):/RustPython -w /RustPython/__doc__ python:slim python generate_docs.py ../RustPython docs.inc.rs
 
+
+and do not forget to update cargo before the test
+```
+$ cargo update
+```
+## Why the `__doc__` is not changed?
+
+### Check the old documentation implemented with remarks are still exist
+RustPython prioritizes the user define documentation. Check if the old remarks are remaining in the source code. If it is, simply removing them could solve the issue.
+
 ## Contributing
 
 Contributions are more than welcome, and in many cases we are happy to guide
@@ -40,4 +50,4 @@ This project is licensed under the MIT license. Please see the
 
 The [project logo](https://github.com/RustPython/RustPython/logo.png) is licensed under the CC-BY-4.0
 license. Please see the [LICENSE-logo](https://github.com/RustPython/RustPython/LICENSE-logo) file
-for more details.
+for more details.