Build `ltitop` documentation

[hidmic]

Rationale

As of today, ltitop has no documentation. That makes it useless for pretty much anyone.

Definition of Done

• [ ] Document project public APIs
  • Use ReST format for docstrings.
• [ ] Document project itself
  • [ ] Add quickstart?
  • [ ] Add overview
  • [ ] Add purpose
  • [ ] Add tutorial?
• [ ] Build project documentation using Sphinx
  • Use RTD theme
• [ ] Use RTD to publish
  • Ensure rebuilds on push to master (use Github webhook).
• [ ] Populate README.md
  • [ ] Add short overview
  • [ ] Add project logo
  • [ ] Add badges
  • [ ] Link to docs

Additional considerations

See this blog post for useful pointers.