console: document the behavior of console.assert()

Add a description and an example of console.assert() call with
no arguments. If called like this, the method should output:
"Assertion failed".

Fixes: https://github.com/nodejs/node/issues/34500
Refs: https://nodejs.org/dist/latest-v14.x/docs/api/console.html#console_console_assert_value_message
Refs: https://console.spec.whatwg.org/#assert

PR-URL: https://github.com/nodejs/node/pull/34501


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>