MAINTAINERS: Add OpenThread maintainers

The OpenThread section is added.

Set rlubos as maintainer and myself as collaborator.

Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>
diff --git a/MAINTAINERS.yml b/MAINTAINERS.yml
index d3e313b..8c3df33 100644
--- a/MAINTAINERS.yml
+++ b/MAINTAINERS.yml
@@ -1178,6 +1178,20 @@
     labels:
         - "area: Networking"
 
+"Networking: OpenThread":
+    status: maintained
+    maintainers:
+        - rlubos
+    collaborators:
+        - pdgendt
+    files:
+        - subsys/net/l2/openthread/
+        - subsys/net/lib/openthread/
+        - samples/net/openthread/
+    labels:
+        - "area: Networking"
+        - "area: OpenThread"
+
 NIOS-2 arch:
     status: maintained
     maintainers: