doc: fix typo on child_process.md

This note on `options.stdio` mentions that it's not recommended to pass
`stdin` as a writable stream and `stdout/stderr` as readable, but then
proceeds to say to always check that `stdin` is writable and
`stdout/stderr` are readable.

Going by the examples and the fact that `process.stdin` is readable and
`process.stdout/process.stderr` are writable, I'm assuming that the
types in the recommendation got swapped.

PR-URL: #60114
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: nglgzz

doc/api/child_process.md

@@ -1068,8 +1068,8 @@ pipes between the parent and child. The value is one of the following:
    them incorrectly (e.g., passing a readable stream where a writable stream is
    expected) can lead to unexpected results or errors. This practice is discouraged
    as it may result in undefined behavior or dropped callbacks if the stream
-   encounters errors. Always ensure that `stdin` is used as writable and
-   `stdout`/`stderr` as readable to maintain the intended flow of data between
+   encounters errors. Always ensure that `stdin` is used as readable and
+   `stdout`/`stderr` as writable to maintain the intended flow of data between
    the parent and child processes.
 7. Positive integer: The integer value is interpreted as a file descriptor
    that is open in the parent process. It is shared with the child