Somewhat recently, we made the change to hide the behavior to save LLDB
session history to the transcript buffer behind the flag
`interpreter.save-transcript`. By default, `interpreter.save-transcript`
is false. See #90703 for context.
I'm making a small update here to our `session save` messaging and some
help docs to clarify for users that aren't aware of this change. Maybe
`interpreter.save-transcript` could be true by default as well. Any
feedback welcome.
# Tests
```
bin/lldb-dotest -p TestSessionSave
```
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Co-authored-by: Tom Yang <toyang@fb.com>
835b5e278e