Manual: table of contents follow reader

[cblanken]

I think the table of contents on the manual page should be pinned to the top of the page to follow along with the reader to make navigation easier for longer sections. As of now, the user must scroll all the way back to the top to navigate to another page of the manual.

Example

LC version 0.14.1

[cblanken]

Similarly, on mobile. But for mobile screens the table of contents should probably be hidden/revealed via a hamburger menu at the top or something similar.