Made docs a bit more beginner friendly

i actually managed to fuck up masking during testing even though i wrote
it, so i figured this might be a nice addition.

epicardium/epicardium.h

@@ -126,9 +126,11 @@ API(API_INTERRUPT_DISABLE, int epic_interrupt_disable(api_int_id_t int_id));
 #define EPIC_INT_UART_RX                2
 /** RTC Alarm interrupt.  See :c:func:`epic_isr_rtc_alarm` */
 #define EPIC_INT_RTC_ALARM              3
+/** Button interrupt */
+#define EPIC_INT_BUTT			4
 
 /* Number of defined interrupts. */
-#define EPIC_INT_NUM                    4
+#define EPIC_INT_NUM                    5
 /* clang-format on */
 
 API_ISR(EPIC_INT_RESET, epic_isr_reset);
@@ -232,7 +234,7 @@ API_ISR(EPIC_INT_CTRL_C, epic_isr_ctrl_c);
  * 
  * Always reads all buttons, use mask=15 for not wasting slow-ish API calls and extract values in pycardium. Note: The reset button cannot be unmapped from reset functionality afaik.
  *
- * :param uint8_t mask: The first 4 LSBs enable readout from corresponding button. The zeroeth bit corresponds to bottom left pin, increasing counterclockwise. If buttons module is imported in micropython also the designators BOTTOM_LEFT, BOTTOM_RIGHT, TOP_RIGHT, TOP_LEFT and RESET can be used with the latter two being identical.
+ * :param uint8_t mask: The first 4 LSBs enable readout from corresponding button. The zeroeth bit corresponds to bottom left pin, increasing counterclockwise, i.e. mask values of 1, 2, 4, 8 read single buttons, others read combinations. If buttons module is imported in micropython also the designators BOTTOM_LEFT, BOTTOM_RIGHT, TOP_RIGHT, TOP_LEFT and RESET can be used with the latter two being identical.
  */
 API(API_BUTTONS_READ, uint8_t epic_buttons_read(uint8_t mask));