Add discussions to readme

[jayjb]

Proposed changes

Add references to our new community health files and guide folks to submit feature requests to the discussion.
Add table of contents for easier navigation.

Types of changes

What types of changes does your code introduce to this repository?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• Lint and unit tests pass locally with my changes (if applicable)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Linked to the relevant github issue or github discussion

Further comments

None

[benjamin-thinkst]

This ordering looks odd to me. How about

• Prerequisites

• Features

• Installation on Ubuntu

• Installation on OS X

• Installation using Git

• Running OpenCanary

• Samba setup for SMB service

• Docker Compose Usage

• Docker Usage

• FAQ

• Contributing

• Code of Conduct

And match this ordering in the main doc below.