Skip to main content links for all pages

[thomcsmits]

Though there is a 'skip to content' link visible with keyboard, it does not skip the website header. https://www.w3.org/TR/WCAG20-TECHS/G1.html

[wangqianwen0418]

Thanks again for creating this PR.

I am not sure which setting you are using, but I have tested the skip to content in both safari and chrome and it works well for all pages (i.e., skip the website headers).

• In the home page, the skip to content directs to the first carousel example
• In the other pages, the skip to content directs to the first section of the page, e.g., http://gosling-lang.org/docs/#create-your-visualization-in-gosling-online-editor in the doc page