doc: add warning to readline's close() method

When close() is called on a readline instance, it is possible
that data is already buffered, and will trigger 'line' events.
This commit adds a warning to the corresponding docs. Note that
a similar warning already exists for the pause() method.

PR-URL: https://github.com/nodejs/node/pull/22679
Fixes: https://github.com/nodejs/node/issues/22615


Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>