doc: add 'everyday' to 'git help'

doc: add 'everyday' to 'git help'

The "Everyday GIT With 20 Commands Or So" is not accessible via the
Git help system.  Move everyday.txt to giteveryday.txt so that "git
help everyday" works, and create a new placeholder file everyday.html
to refer people who follow existing URLs to the updated location.

giteveryday.txt now formats well with AsciiDoc as a man page and
refreshed content to a more command modern style.

Add 'everyday' to the help --guides list and update git(1) and 5
other links to giteveryday.

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