script.1: Improve documentation of non-interactive behavior

script.1: Improve documentation of non-interactive behavior

- use exit in .profile to avoid non-logged session after typing "exit"
- document that script can read more from stdin than the command inside:

echo -e 'script -c "read a b ; echo a=\$a b=\$b >defs.sh"\n1 2\necho Done' | sh
Script started, file is typescript
1 2
echo Done
Script done, file is typescript