doc: standardize on "host name" in dgram.md

Our docs have a mix of "hostname" and "host name" in prose.

Let's follow the usage of Unix man pages, RFCs, and most
professionally-edited sources, and use "host name" in prose and
"hostname" to refer to the command and in code.

Lint rule forthcoming.

PR-URL: nodejs#31326
Refs: nodejs#31073
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

doc/api/dgram.md

@@ -400,7 +400,7 @@ changes:
 * `offset` {integer} Offset in the buffer where the message starts.
 * `length` {integer} Number of bytes in the message.
 * `port` {integer} Destination port.
-* `address` {string} Destination hostname or IP address.
+* `address` {string} Destination host name or IP address.
 * `callback` {Function} Called when the message has been sent.
 
 Broadcasts a datagram on the socket.