index.html: Link to wiki articles

Signed-off-by: Jordan Justen <jljusten@gmail.com>
index.html: Fix 'Release Notes' url

Signed-off-by: Jordan Justen <jljusten@gmail.com>
layout: Center entire webpage

Signed-off-by: Jordan Justen <jljusten@gmail.com>
layout: Shrink width from 70 to 60em

Signed-off-by: Jordan Justen <jljusten@gmail.com>