Remove facebook comments feature in facebook_comment.ejs and _config.yml.
But remain facebook_comment.ejs for demander.

Signed-off-by: acgtyrant <acgtyrant@gmail.com>
Change favicon's formant from png to ico

Signed-off-by: acgtyrant <acgtyrant@gmail.com>
Add /about & /RSS pages and atom.xml in _config.yml

Signed-off-by: acgtyrant <acgtyrant@gmail.com>
Add some notes about Favicon & RSS, and update others section.

Signed-off-by: acgtyrant <acgtyrant@gmail.com>