MAINTAINER: add myself as kernel collaborator

Confirm candidacy as kernel collaborator.

Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
diff --git a/MAINTAINERS.yml b/MAINTAINERS.yml
index d13966d..26a6883 100644
--- a/MAINTAINERS.yml
+++ b/MAINTAINERS.yml
@@ -883,6 +883,7 @@
         - nashif
         - ceolin
         - dcpleung
+        - pabigot
     files:
         - doc/reference/kernel/
         - include/kernel*.h