feat(config): add some more config options (#64)

## Add
Make these things configurable
- Expand aliases
- Suggest hidden files (#59)
- Toggle menu and mode 

```
[ui]
hidden-files = true # or false

[core]
expand-alias = true # or false

[keybindings]
toggle-mode = "ctrl+r"
toggle-menu = "ctrl+space"
```

- Auto reload config on changes: now just changes config and save the
file, IRIS will auto detect and reload in silent
- Added all these in config on init and docs

## Fix
I tested on holding backspace and the ghost text keep glitching so I
fixed it, this is just a small fix

docs/README.md

@@ -107,14 +107,20 @@ version = 1
 shell = ""        # "zsh", "bash", "fish", or empty for auto-detection
 mode = "last"     # "last", "spec", or "history"
 debug = false
+expand-alias = true
 
 [ui]
 style = "modern"  # "modern" or "classic"
 ghost-text = true
+hidden-files = false
 max-suggestions = 100
 max-height = 15
 nerd-fonts = true
 
+[keybindings]
+toggle-mode = "ctrl+r"
+toggle-menu = "ctrl+space"
+
 [git]
 filter-active-branch = true
 deduplicate-branches = true