Use only the `title: ` attribute in the frontmatter for titles, avoid duplicating title in Markdown

[elichad]

Bert: Use only the title: attribute in the frontmatter for titles. This one is used in the page metadata + will render to a title with edit me buttons next to it, which improves the contributing experience of community members. (if you did not change it to much in the layout)

Eli: suspect we have overridden this behaviour