Changed . token to _dot

This change allows the dotfiles to work with chezmoi (e.g: on windows)
and improves grepability with neovim/telescope

dot_config/nushell/nu_scripts/modules/prompt/README.md

@@ -0,0 +1,31 @@
+# Prompt Scripts
+
+### Definition
+
+These scripts should be used to draw a custom command prompt in nushell. They can include anything that we think is appropriate for prompts such as `git` commands, `starship`, `oh-my-posh`, etc.
+
+#### starship.nu
+
+File is in [starship](./starship.nu)
+
+This describe how to use starship to make a leftprompt, the repo of starship is [here](https://github.com/starship/starship).
+
+This script set the output of starship as leftprompt
+
+![starshipshow](./images/starship.png)
+
+#### shell_space.nu
+
+File is in [shell_space](./shell_space.nu)
+
+Use the function of shells in nu, you can view the function with the command following
+
+```
+help shells
+```
+
+![shell_spaceshow](./images/shell_space.png)
+
+#### jalon-git.nu
+From https://github.com/JalonWong/nushell-prompt
+![jalon-git](./images/jalon-git.png)