Add documentation for Anel NET-PwrCtrl PDU Plugin (#959)

* Add documentation for Anel NET-PwrCtrl PDU Plugin

* sync documentation with plugin updates

---------

Co-authored-by: Peter Schumann <peter.schumann@secunet.de>

docs/gpio.md

@@ -525,3 +525,36 @@ kvmd
                     - ["plug_led", "plug_button"]
 
     ```
+### ANEL NET-PwrCtrl
+??? note "Click to view"    
+    The `anelpwr` plugin allows you to use ANEL NET-PwrCrtl IP-PDUs (switchabel sockets) as gpios. There are up to 8 Ports per PDU. Input pulls the the current state from the PDU, Output switches the Socket. 
+
+    ```yaml
+    kvmd:
+	gpio:
+        drivers:
+            anel_pdu_1:
+		        type: anelpwr
+		        url: http://IP:Port/
+		        user: admin
+		        passwd: anel
+		        initial: null
+	    scheme:
+            pdu1_1_pwr:
+			    pin: 1
+			    driver: anel_pdu_1
+			    mode: output
+			    pulse:
+			        delay: 0
+	        pdu1_1_led:
+			    pin: 1
+			    driver: anel_pdu_1
+			    mode: input
+	    view:
+            header:
+		       title: "PDUs"
+            table:
+		        - ["#PDU1"]
+                - []
+                - ["#PDU1_Port1:", pdu1_1_led, "pdu1_1_pwr|confirm|test"] 
+    ```