doc: fix typo in child_process.md

PR-URL: #17727
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

doc/api/child_process.md

@@ -980,7 +980,7 @@ added: v0.1.90
 
 * `signal` {string}
 
-The `subprocess.kill()` methods sends a signal to the child process. If no
+The `subprocess.kill()` method sends a signal to the child process. If no
 argument is given, the process will be sent the `'SIGTERM'` signal. See
 signal(7) for a list of available signals.