fix(doc): Fix vibra docs

Signed-off-by: Rahix <rahix@rahix.de>

epicardium/epicardium.h

@@ -10,6 +10,7 @@
 #define API_UART_WRITE         0x1
 #define API_UART_READ          0x2
 #define API_LEDS_SET           0x3
+#define API_VIBRA_SET          0x4
 /* clang-format on */
 
 /**
@@ -53,8 +54,16 @@ API(API_UART_READ, char epic_uart_read_chr(void));
  */
 API(API_LEDS_SET, void epic_leds_set(int led, uint8_t r, uint8_t g, uint8_t b));
 
-// turn vibration motor on or off
-#define API_VIBRA_SET  0x4
+/**
+ * Misc
+ * ====
+ */
+
+/**
+ * Turn vibration motor on or off
+ *
+ * :param status: 1 to turn on, 0 to turn off.
+ */
 API(API_VIBRA_SET, void epic_vibra_set(int status));
 
 #endif /* _EPICARDIUM_H */