* doc/bison.texinfo: Use `$' as shell prompt, not `%'.

* doc/bison.texinfo: Use `$' as shell prompt, not `%'.
Use @kbd to denote user input.
(Language and Grammar): ANSIfy the example.
Adjust its layout for info/notinfo.
(Location Tracking Calc): Output error messages to stderr.
Output locations in a more GNUtically correct way.
Fix a couple of Englishos.
Adjust @group/@end group pairs.