doc: fix documentation for input option in child_process

PR-URL: nodejs#49481
Fixes: nodejs#49417
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Chemi Atlow <chemi@atlow.co.il>

doc/api/child_process.md

@@ -925,8 +925,8 @@ changes:
 * `options` {Object}
   * `cwd` {string|URL} Current working directory of the child process.
   * `input` {string|Buffer|TypedArray|DataView} The value which will be passed
-    as stdin to the spawned process. Supplying this value will override
-    `stdio[0]`.
+    as stdin to the spawned process. If `stdio[0]` is set to `'pipe'`, Supplying
+    this value will override `stdio[0]`.
   * `stdio` {string|Array} Child's stdio configuration. `stderr` by default will
     be output to the parent process' stderr unless `stdio` is specified.
     **Default:** `'pipe'`.
@@ -995,8 +995,8 @@ changes:
 * `options` {Object}
   * `cwd` {string|URL} Current working directory of the child process.
   * `input` {string|Buffer|TypedArray|DataView} The value which will be passed
-    as stdin to the spawned process. Supplying this value will override
-    `stdio[0]`.
+    as stdin to the spawned process. If `stdio[0]` is set to `'pipe'`, Supplying
+    this value will override `stdio[0]`.
   * `stdio` {string|Array} Child's stdio configuration. `stderr` by default will
     be output to the parent process' stderr unless `stdio` is specified.
     **Default:** `'pipe'`.
@@ -1071,11 +1071,11 @@ changes:
 * `options` {Object}
   * `cwd` {string|URL} Current working directory of the child process.
   * `input` {string|Buffer|TypedArray|DataView} The value which will be passed
-    as stdin to the spawned process. Supplying this value will override
-    `stdio[0]`.
+    as stdin to the spawned process. If `stdio[0]` is set to `'pipe'`, Supplying
+    this value will override `stdio[0]`.
   * `argv0` {string} Explicitly set the value of `argv[0]` sent to the child
     process. This will be set to `command` if not specified.
-  * `stdio` {string|Array} Child's stdio configuration.
+  * `stdio` {string|Array} Child's stdio configuration. **Default:** `'pipe'`.
   * `env` {Object} Environment key-value pairs. **Default:** `process.env`.
   * `uid` {number} Sets the user identity of the process (see setuid(2)).
   * `gid` {number} Sets the group identity of the process (see setgid(2)).