generating "," instead of keeping it in repository

readme.md

@@ -2,5 +2,21 @@
 
 Personal tools set written in Golang.
 
-To use it just clone and add the directory to *PATH*.
-Then type "," command, all commands will appear.
+## How to run
+
+0. Clone this repository to somewhere
+0. Add the root directory to *PATH*
+0. change directory to the root directory
+0. Run `go run .` to generate "," command
+0. Run "," command to see all commands
+
+"," command can auto rebuild if you change the code in this repository.
+Actually it always builds each time you type it! Because `go build` is
+very fast and it has cache, it's not a problem in terms of speed.
+
+## Q&A
+
+Q: Why generating "," shell script instead of putting it in repository?
+
+A: I like the repository keeps 100% Go source code. I tried writting ","
+shell script as a Go source code with shebang, but it didn't work.