hover texts for all interface elements

[kohlhase]

I really like the hover text for the new "report an issue button". All interface elements should have hover texts like this one. Here are some proposed texts:

• statistics: statistics about contents of the current library|archive|file|... (where the correct level is named
• responsible: the person responsible for curating the content of this library|archive|file|...
• view source: view/edit the source of this library|archive|file|... in the MathHub repository

and then the top-level menu items (can they have hover texts at all)

• MathHub: Active Flexiformal Mathematics
• About: `Find out more about MathHub (Documentation)
• Applications: `Mathematical Services that feed on MathHub content'

It would be great, if the hover texts were in a separate file somewhere, where they could be updated(supplied) by people like me without having to understand the code.
@tkw1536 could you comment?

[tkw1536]

I think having hover texts for all elements would be great.