feat(docs): Document and define different RGB effects

Co-Authored-By: Cem Aksoylar <caksoylar@users.noreply.github.com>

Author: ReFil

app/include/dt-bindings/zmk/rgb.h

@@ -38,4 +38,9 @@
 #define RGB_MEFS RGB_MEFS_CMD
 #define RGB_COLOR_HSB_VAL(h, s, v) (((h) << 16) + ((s) << 8) + (v))
 #define RGB_COLOR_HSB(h, s, v) RGB_COLOR_HSB_CMD##(RGB_COLOR_HSB_VAL(h, s, v))
-#define RGB_COLOR_HSV RGB_COLOR_HSB
+#define RGB_COLOR_HSV RGB_COLOR_HSB
+
+#define RGB_EFF_SOLID 0
+#define RGB_EFF_BREATHE 1
+#define RGB_EFF_SPECTRUM 2
+#define RGB_EFF_SWIRL 3

docs/docs/keymaps/behaviors/underglow.md

@@ -98,6 +98,12 @@ If the `RGB_MEFS` key is held down for longer than [`CONFIG_ZMK_SETTINGS_SAVE_DE
    &rgb_ug RGB_COLOR_HSB(128,100,100)
    ```
 
+1. Select a specific RGB effect (Swirl)
+
+   ```dts
+   &rgb_ug RGB_EFS RGB_EFF_SWIRL
+   ```
+
 ## Split Keyboards
 
 RGB underglow behaviors are [global](../../features/split-keyboards.md#global-locality-behaviors): This means that when triggered, they affect both the central and peripheral side of split keyboards.