doc: minor correction to note on process section

PR-URL: nodejs/node#16311
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Nicu Micleușanu <micnic90@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

Author: danbev

doc/api/process.md

@@ -1676,7 +1676,7 @@ important ways:
    respectively.
 2. They cannot be closed ([`end()`][] will throw).
 3. They will never emit the [`'finish'`][] event.
-4. Writes may be synchronous depending on the what the stream is connected to
+4. Writes may be synchronous depending on what the stream is connected to
    and whether the system is Windows or POSIX:
    - Files: *synchronous* on Windows and POSIX
    - TTYs (Terminals): *asynchronous* on Windows, *synchronous* on POSIX