Add new icons to enum (#381)

src/raygui.h

@@ -971,9 +971,9 @@ typedef enum {
     ICON_FOLDER                   = 217,
     ICON_FILE                     = 218,
     ICON_SAND_TIMER               = 219,
-    ICON_220                      = 220,
-    ICON_221                      = 221,
-    ICON_222                      = 222,
+    ICON_WARNING                  = 220,
+    ICON_HELP_BOX                 = 221,
+    ICON_INFO_BOX                 = 222,
     ICON_223                      = 223,
     ICON_224                      = 224,
     ICON_225                      = 225,