MAINTAINERS: update nRF platform files

Add missing tests, drivers and Nordic-specific
snippets.

Signed-off-by: Marcin Szymczyk <marcin.szymczyk@nordicsemi.no>

MAINTAINERS.yml

@@ -3464,12 +3464,14 @@ nRF Platforms:
     - anangl
   files:
     - boards/nordic/
-    - drivers/*/*nrfx*.c
+    - drivers/*/*nrf*.c
+    - drivers/*/*nordic*/
     - soc/nordic/
     - samples/boards/nrf/
     - dts/*/nordic/
     - dts/bindings/*/nordic,*
-    - tests/drivers/timer/nrf_rtc_timer/
+    - tests/drivers/*/*nrf*/
+    - snippets/nordic*/
   labels:
     - "platform: nRF"