doc: modernise everyday.txt wording and format in man page style

Refresh the contents of everyday.txt contents to a more modern
command style. Also update the mark-up so that it can be formatted
as a man page with AsciiDoc ready for transfer to the Git guides.
The transfer is in subsequent commits.

Guidance on modernising the command style provided by Junio at [1],
[2] and [3].

[1] Individual Developer, both Standalone and Participant
http://article.gmane.org/gmane.comp.version-control.git/254269
[2] Integrator
http://article.gmane.org/gmane.comp.version-control.git/254502
[3] Administrator
http://article.gmane.org/gmane.comp.version-control.git/254824

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Philip Oakley <philipoakley@iee.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>