[Keymap] Jonavin merc additional encoder functionality (#13039)

Co-authored-by: Drashna Jaelre <drashna@live.com>
Co-authored-by: Jonavin <=>

keyboards/mechwild/mercutio/keymaps/jonavin/readme.md

@@ -12,5 +12,29 @@ Features
   - MOUSEKEYS is disbled
   - shutdown oled when powered down to prevent OLED from showing Mercutio all the time
   - add WPM indicator when wpm is > 20 wpm
+  - add double tap of Left Shift to toggle Caps Lock
+  
+  - FN layer has encoder selectable key codes and displayed on OLED
+        
+        Change these in keymap.c to assign your desired key selection
 
+        static const keycodedescType PROGMEM keyselection[] = {
+            // list of key codes that will be scrollled through by encoder and description
+                {"TASK",    KC_TASK},
+                {"INS",     KC_INS},
+                {"DEL",     KC_DEL},
+                {"PrtSc",   KC_PSCR},
+                {"ScrLk",   KC_SCLN},
+                {"Break",   KC_PAUS},
+                {"C-A-D",   KC_CAD},  // Ctrl-Alt-Del
+                {"AltF4",   KC_AF4},
+                {"PLAY",    KC_MEDIA_PLAY_PAUSE}
+        };
+
+  - Additional encoder functionality 
+        While holding Left Ctrl, navigates next or previous word
+        While holding Left Alt, media next track or previous track
+
+
+Default Layers
 ![image](https://user-images.githubusercontent.com/71780717/118902752-4aaf7880-b8e4-11eb-82f4-e5047612ffcf.png)