docs: `smart_sort` should be documented about atuin HOT 2 OPEN

Thanks for the issue! I've actually left it as undocumented for a while now intentionally, as while it seemed to work I wanted to test it some more before advertising it and committing to supporting it. It's probably fine now though

from atuin.

and #1599

Its a great idea. +10 useful points.

edit - Perhaps it could be put into the config, but as

[experimental]
## CAUTION. Here be dragons!
## these settings are experimental. Refer to Github and/or doco.
# smart_sort=true

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