Update shell.md

Author: ZhikangNiu

src/useful/shell.md

@@ -5,3 +5,4 @@
 - [Bash scripting cheatsheet](https://devhints.io/bash)
 - [The art of command line](https://github.com/jlevy/the-art-of-command-line/blob/master/README-zh.md)
 - [bash.academy](https://guide.bash.academy/): This guide is an introduction to basic and advanced concepts of the bash shell.
+- [Shell学习与开发的资料](https://github.com/oldratlee/useful-scripts/blob/dev-3.x/docs/developer-guide.md)