Indicator LEDs as config (#10816)

* First pass

* Add config options to docs

* Update some wording

* Slight tidy up of backlight caps logic

* Init pin to correct state

* Move init location

* Reverse default state

keyboards/cospad/config.h

@@ -53,6 +53,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 #define SOFT_SERIAL_PIN D0  // or D1, D2, D3, E6
 
+#define LED_NUM_LOCK_PIN B2
+#define LED_PIN_ON_STATE 0
+
 #define BACKLIGHT_PIN F7
 // #define BACKLIGHT_BREATHING
 #define BACKLIGHT_LEVELS 3