Use ARRAY_SIZE in docs (found by grep)

docs/feature_combo.md

@@ -255,7 +255,7 @@ bool combo_should_trigger(uint16_t combo_index, combo_t *combo, uint16_t keycode
 ```
 
 ## Variable Length Combos
-If you leave `COMBO_COUNT` undefined in `config.h`, it allows you to programmatically declare the size of the Combo data structure and avoid updating `COMBO_COUNT`. Instead a variable called `COMBO_LEN` has to be set. It can be set with something similar to the following in `keymap.c`: `uint16_t COMBO_LEN = sizeof(key_combos) / sizeof(key_combos[0]);` or by adding `COMBO_LENGTH` as the *last* entry in the combo enum and then `uint16_t COMBO_LEN = COMBO_LENGTH;` as such:
+If you leave `COMBO_COUNT` undefined in `config.h`, it allows you to programmatically declare the size of the Combo data structure and avoid updating `COMBO_COUNT`. Instead a variable called `COMBO_LEN` has to be set. It can be set with something similar to the following in `keymap.c`: `uint16_t COMBO_LEN = ARRAY_SIZE(key_combos);` or by adding `COMBO_LENGTH` as the *last* entry in the combo enum and then `uint16_t COMBO_LEN = COMBO_LENGTH;` as such:
 ```c
 enum myCombos {
     ...,