Docs index: features to orient the user

[fredrik-bakke]

The problem

On the main page of the docs, when you scroll through all of the modules or follow a reference to a specific place in this index, it is not necessarily clear which namespace the given modules you're looking at are in, or even what the precise name of that module is.

Consider for instance Two natural questions I repeatedly want a quick answer to here is:

1. Is this in the index of modules in foundation or foundation-core?
2. What's the module name for "Commuting 3-simplices of maps" for instance?

Two suggestions

To improve this, I propose two solutions

1. Have the module names in some less aggressive color such as light gray next to each index entry
2. Have the current namespace as a sticky header on the page.

An illustration incorporating both ideas:

Although it probably looks neater if the module names are aligned as well.