SUBSYSTEMS.md: Adding myself to the relevant parts

SUBSYSTEMS.md

@@ -84,16 +84,32 @@ affect more than one module.
 ## Network stacks
 ### GNRC
 
-#### IPv6 Auto-Subnetting
+- Martine S. Lenders (@miri64)
+
+#### 6LowPAN
+
+- Martine S. Lenders (@miri64)
+
+#### IPv6
+
+- Martine S. Lenders (@miri64)
+
+##### Auto-Subnetting
 
  - Benjamin Valentin (@benpicco)
 
+#### UDP
+
+- Martine S. Lenders (@miri64)
+
 ### CCN-Lite
 
 ### OpenThread
 
 ### LWIP
 
+- Martine S. Lenders (@miri64)
+
 ### OpenWSN
 
 ## Physical/Link Layer
@@ -106,12 +122,12 @@ affect more than one module.
 ## Interfaces
 ### Sock
 
+- Martine S. Lenders (@miri64)
+
 ### Netif
 
 ### Netdev
 
-## 6LowPAN
-
 ## Application protocols
 ### CoAP
 
@@ -127,6 +143,8 @@ affect more than one module.
 
 ### DTLS
 
+- Martine S. Lenders (@miri64)
+
 ### RPL
 
 # Build System