Revise Navigation Column In Hugo Output

[reid-spencer]

Currently, the navigation section on the left of the hugo output isn't particularly helpful. The issue is the length of the keys and the non-adjustable width of the navigation column (see thegeeklab/hugo-geekdoc#325). Instead, we need to break it into section "indexes". The suggestion is to:

Make the index only go to the depth of Domains and Contexts and provide individual index pages for each of them. So the navigation bar would look like:

• Domains → open/close the list of domains
  ** Domain1 → shows index for Domain1: Contexts, Epics, Applications, ... each type with a header and sorted alphabetically
  *** Contexts → open/close the list of Contexts in Domain1
  **** Context1 → shows index for Context1: Adaptors, Entities, Types, Repositories, Projectors, Streamlets, ... each type with
  a header and sorted alphabetically.
  **** Context2 → shows index for Context1: Adaptors, Entities, Types, Repositories, Projectors, Streamlets, ... similarly
  ** Domain2 → shows index for Domain 2: Context, Epics, Applications, ... similarly as Domain1