[todo] update documentations

[aviatesk]

We have such a beautiful documentation, and it can be even nicer.

Here are several TODOs I'm recognising now:

• updates on basic stuff:
  • [x] update version number of Atom, Julia, links
  • [x] update where/how to report issues and communicate with us
• Update screenshots in https://junolab.org so that they will reflect our recent UIs and new features:
  • [ ] outline view
  • [ ] completions including local bindings
  • [ ] debugger pane
  • [ ] goto & hyperclick
• explanations for the usage documentation pane -- there are several undocumented tips in that
  • [ ] regenerate documentation cache
  • [ ] add explanations for search options
  • [ ] show module description (README)
• add description for our recent features by static code-analysis
  • [ ] outline view
  • [ ] goto symbols (from editor/docs/workspace)
  • [ ] rename refactor (to be implemented)

Feel free to add anything you want :)