doc: immprove inode text in fs.md

Rewrite and edit somewhat confusing paragraph about inodes and AIX in
fs.md.

PR-URL: #17519
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Trott

doc/api/fs.md

@@ -2568,12 +2568,9 @@ a new inode. The watch will emit an event for the delete but will continue
 watching the *original* inode. Events for the new inode will not be emitted.
 This is expected behavior.
 
-On AIX, save and close of a file being watched causes two notifications -
-one for adding new content, and one for truncation. Moreover, save and
-close operations on some platforms cause inode changes that force watch
-operations to become invalid and ineffective. AIX retains inode for the
-lifetime of a file, that way though this is different from Linux / macOS,
-this improves the usability of file watching. This is expected behavior.
+AIX files retain the same inode for the lifetime of a file. Saving and closing a
+watched file on AIX will result in two notifications (one for adding new
+content, and one for truncation).
 
 #### Filename Argument