doc: improve fs.read() doc text

PR-URL: #14631
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

doc/api/fs.md

@@ -1308,9 +1308,9 @@ Read data from the file specified by `fd`.
 
 `length` is an integer specifying the number of bytes to read.
 
-`position` is an integer specifying where to begin reading from in the file.
-If `position` is `null`, data will be read from the current file position, 
-and the file position will be updated for subsequent reads.
+`position` is an argument specifying where to begin reading from in the file.
+If `position` is `null`, data will be read from the current file position,
+and the file position will be updated.
 If `position` is an integer, the file position will remain unchanged.
 
 The callback is given the three arguments, `(err, bytesRead, buffer)`.