doc: APIs: group display drivers

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/include/display/grove_lcd.h b/include/display/grove_lcd.h
index 8bc9458..dfa1b55 100644
--- a/include/display/grove_lcd.h
+++ b/include/display/grove_lcd.h
@@ -11,6 +11,20 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Display Drivers
+ * @defgroup display_interfaces Display Drivers
+ * @{
+ * @}
+ */
+
+/**
+ * @brief Grove display APIs
+ * @defgroup grove_display Grove display APIs
+ * @ingroup display_interfaces
+ * @{
+ */
+
 #define GROVE_LCD_NAME			"GLCD"
 
 /**
@@ -156,6 +170,11 @@
  */
 int glcd_initialize(struct device *port);
 
+
+/**
+ * @}
+ */
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/display/mb_display.h b/include/display/mb_display.h
index 6d1237b..24e2e31 100644
--- a/include/display/mb_display.h
+++ b/include/display/mb_display.h
@@ -14,6 +14,7 @@
 /**
  * @brief BBC micro:bit display APIs
  * @defgroup mb_display BBC micro:bit display APIs
+ * @ingroup display_interfaces
  * @{
  */