Added Offset and links to headlines

Added offset: Now has the description on how to use the offset-feature
in the smooth-scroll component.

Added links and id to headlines: This is in preparation of making
headlines of each site directly linkable for easier support.
Added uk-link-reset to headline-links
updated docs - smooth scroll
Extended all H2 Headlines with an ID and a link

All H2s have now an ID and the text inside of the headlines is wrapped
into a link with uk-link-reset.

This is in preparation of making H2 headlines of each site directly
linkable (with #) for easier support.
Extended all H2 Headlines with an ID and a link

All H2s have now an ID and the text inside of the headlines is wrapped
into a link with uk-link-reset.

This is in preparation of making H2 headlines of each site directly
linkable (with #) for easier support.