Add key-binding configuration README

README.md

@@ -63,7 +63,10 @@ q | Ctrl+c - [q]uit
 [w,a,s,d,?] >> [INPUT HERE]
 ```
 
-> The movement controls have been derived from both the world of gamers (WASD) and VIM users (HJKL).
+### ⚙️ Customization
+
+The above key-bindings can be altered by creating a `.fac.yml` file in your home directory.
+Please refer to the [configuration README.md](./key/README.md) for more information.
 
 ## ✋ Contributing
 

key/README.md

@@ -0,0 +1,46 @@
+# ⚙️  Configuration
+
+## .fac.yml
+
+Configure fac by adding a `.fac.yml` in your `$HOME` directory. With the file in place, the following paramters can be configued:
+
+```yml
+select_local: a
+select_incoming: b
+toggle_view: c
+show_up: d
+show_down: e 
+scroll_up: f
+scroll_down: g
+edit: h
+next: i
+previous: j
+quit: k
+help: l
+```
+
+## 📖  Rules
+
+When parsing `.fac.yml`, fac enforces *three rules.*
+
+### 1. Invalid key-binding keys
+```yml
+foobar: f
+```
+
+> Warning: Invalid key: "fobar" will be ignored
+
+### 2. Multi-character key-mappings
+```yml
+select_local: local
+```
+
+> Warning: Illegal multi-character mapping: "local" will be interpreted as 'l'  
+
+### 3. Duplicate key-mappings
+```yml
+show_up: u
+scroll_up: u
+```
+
+> Fatal: Duplicate key-mapping: "scroll_up, show_up" are all represented by 'u'