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: #22679
Fixes: #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>

Author: cjihrig

doc/api/readline.md

@@ -195,6 +195,9 @@ The `rl.close()` method closes the `readline.Interface` instance and
 relinquishes control over the `input` and `output` streams. When called,
 the `'close'` event will be emitted.
 
+Calling `rl.close()` does not immediately stop other events (including `'line'`)
+from being emitted by the `readline.Interface` instance.
+
 ### rl.pause()
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