docs/library/network: Add dhcp_hostname parameter

I have not actually tested this, going by information available in https://forum.micropython.org/viewtopic.php?t=2584

docs/library/network.rst

@@ -422,16 +422,17 @@ parameter should be `id`.
        Following are commonly supported parameters (availability of a specific parameter
        depends on network technology type, driver, and `MicroPython port`).
 
-       =========  ===========
-       Parameter  Description
-       =========  ===========
-       mac        MAC address (bytes)
-       essid      WiFi access point name (string)
-       channel    WiFi channel (integer)
-       hidden     Whether ESSID is hidden (boolean)
-       authmode   Authentication mode supported (enumeration, see module constants)
-       password   Access password (string)
-       =========  ===========
+       =============  ===========
+       Parameter      Description
+       =============  ===========
+       mac            MAC address (bytes)
+       essid          WiFi access point name (string)
+       channel        WiFi channel (integer)
+       hidden         Whether ESSID is hidden (boolean)
+       authmode       Authentication mode supported (enumeration, see module constants)
+       password       Access password (string)
+       dhcp_hostname  The DHCP hostname to use
+       =============  ===========