Document the TTY option

[martindsouza]

If SQLcl is being run like echo exit | sqlcl giffy/giffy@localhost:32118/xepdb1 @myscript it needs to not have TTY. This case it may make sense to have two aliases (or Functions - see #10). One for no-tty (i.e. remove the -t option - but keep the -i) and one with.