Revert "docs: make the website navbar stick to top"
Revert "docs: make the website navbar stick to top"

Unfortunately this breaks the anchor links - the titles are under the
navbar, so revert this for the moment.

This reverts commit cdfb3f7194930b81c8d26c3d773bcb843a765721.

ncw/rclone,ncw/rclone,ncw/rclone,ncw/rclone