Gemfile: add dependency on sitemap_generator gem

This is to generate the sitemap automatically.

Signed-off-by: diditclear <didyourupgradeclear@gmail.com>
robots: remove robots.txt

This is installation specific.

Signed-off-by: diditclear <didyourupgradeclear@gmail.com>
layout: add description

Signed-off-by: diditclear <didyourupgradeclear@gmail.com>
index: add links to tos and privacy policy

Signed-off-by: diditclear <didyourupgradeclear@gmail.com>