Documentation: corrections to console/console.txt

Fix typos, line length, grammar, punctuation, and capitalization
in console.txt.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Antonino A. Daplas <adaplas@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>