Create a structure for the TDT documentations

[AvolaAmg]

This issue is needed to keep track of the main structure of the documentation. Please tag the tickets related to each section as they come.

The current structure can be found here.

An updated structure could go as follows (open to discussion feel free to add comments about the sections):

1. Install requirements
2. Quick Start
3. Create a new repo
4. User Interface
   1. Table
      1. Switch system tables
      2. User tables
   2. Table management
      1. Adding new records
      2. Editing existing data
      3. Sorting and filtering data
   3. Actions this part needs to be changed once the action button is modified
      1. Save
      2. GitHub control
      3. Make a release
      4. Publish PURL
      5. Export CAS Json
      6. Export to Anndata
   4. Views
   5. How to guides - how to work with the taxonomy in this guide we could explain the step by step procedures of how to use the TDT and how to annotate cell sets
      1. Start curating taxonomies
      2. Adding new cell types with new cell ontology terms
      3. Changing an obsolete cell term
      4. Saving your progress
      5. Releasing your progress to the repository
      6. Export your data
   6. Additional links
      1. Intro to taxonomy development tools
      2. How to create a GitHub account
      3. How make a pull request in TDT
      4. Cell Annotation Schema
      5. PURL