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/sourced/README.md

@@ -0,0 +1,13 @@
+# Helpers
+
+Commands to make your life easier.
+
+## How to use
+
+Execute following snippet at any time to be able to run the commands in the scripts:
+
+```zsh
+source './path/to/script.nu'
+```
+
+With `./path/to/...` being the path to the script you want to utilize.