Docs should have an "overview" of methods

[calum-chamberlain]

The docs have gotten a bit to technical in places, which, I think, makes them hard to follow. I think they would benefit from method overviews at the top of each of the tutorial pages, where each step links to the appropriate technical section.

There also isn't much to help out with looping over data segments, or using your own continuous data for Tribe.detect (currently the tutorial is focused on data downloaded on the fly).

To do:

• Overview for each method:
  • matched-filter
  • subspace
  • lag-calc
• Better examples for looping over data chunks
• How to use your own data.

[calum-chamberlain]

This should go alongside #187