Create package structure outline

[andrewtavis]

wikirepo as a project has many modules that interconnect and are funneled to two functions - wikirepo.data.query and lctn_utils.gen_lctns_dict. It would be helpful for users and potential contributors to have a visual representation of the package that details the overarching structure and the purpose of various components. This outline could then be added to the readme in the To-Do section, potentially in a drop down.

An initial test of this could be as simple as a directory outline that has a bit more detail about the given components - say by using *, **, †, ‡ and other symbols to indicate where a description could be found.

A discussion of how to best present the package structure is more than welcome, and contributions would further be very appreciated!