doc: fixed a typo in process.md

If the process was not spawned with an IPC channel, `process.send`
will be undefined and calling it as `process.send()` would throw error

PR-URL: #30277
Reviewed-By: Anna Henningsen <anna@addaleax.net>

doc/api/process.md

@@ -1957,7 +1957,7 @@ If Node.js is spawned with an IPC channel, the `process.send()` method can be
 used to send messages to the parent process. Messages will be received as a
 [`'message'`][] event on the parent's [`ChildProcess`][] object.
 
-If Node.js was not spawned with an IPC channel, `process.send()` will be
+If Node.js was not spawned with an IPC channel, `process.send` will be
 `undefined`.
 
 The message goes through serialization and parsing. The resulting message might