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

internal/config/defaults.go

@@ -5,17 +5,19 @@ import "time"
 func DefaultConfig() *Config {
 	return &Config{
 		Core: CoreConfig{
-			Version: 1,
-			Shell:   "",
-			Mode:    "last",
-			Debug:   false,
+			Version:     1,
+			Shell:       "",
+			Mode:        "last",
+			Debug:       false,
+			ExpandAlias: true,
 		},
 		UI: UIConfig{
-			Style:          "modern",
-			GhostText:      true,
-			MaxSuggestions: 100,
-			MaxHeight:      15,
-			NerdFonts:      true,
+			Style:           "modern",
+			GhostText:       true,
+			ShowHiddenFiles: false,
+			MaxSuggestions:  100,
+			MaxHeight:       15,
+			NerdFonts:       true,
 		},
 		Git: GitConfig{
 			FilterActiveBranch:  true,
@@ -38,6 +40,10 @@ func DefaultConfig() *Config {
 				MinIntervalMS: 5000,
 			},
 		},
+		Keybindings: KeybindingsConfig{
+			ToggleMode: "ctrl+r",
+			ToggleMenu: "shift+tab",
+		},
 	}
 }