Merge bitcoin#30946: doc: correct the zmq automatic build info

06e7e83 doc: correct the zmq automatic build info (tdb3)

Pull request description:

  The current documentation states that the ZMQ feature is automatically included when building.
  Noticed this was no longer the case when building to review PR bitcoin#30942.

ACKs for top commit:
  l0rinc:
    ACK 06e7e83
  hebasto:
    re-ACK 06e7e83.

Tree-SHA512: 24269c29415e54815b105e3f830f31f055e9bdcb3bf4a7cede068651875190adfc4e72ad5448b3c30a23b0db024f743d9f18576a6fda46d87deb5ea39352e626

doc/zmq.md

@@ -46,11 +46,10 @@ operation.
 
 ## Enabling
 
-By default, the ZeroMQ feature is automatically compiled in if the
-necessary prerequisites are found.  To disable, use -DWITH_ZMQ=OFF
-during the *configure* step of building bitcoind:
+By default, the ZeroMQ feature is not automatically compiled.
+To enable, use `-DWITH_ZMQ=ON` when configuring the build system:
 
-    $ cmake -B build -DWITH_ZMQ=OFF (other options)
+    $ cmake -B build -DWITH_ZMQ=ON
 
 To actually enable operation, one must set the appropriate options on
 the command line or in the configuration file.