chore: deep link documentation for registering proposals

[maxwellmattryan]

Summary

Please summarize your changes, describing what they are and why they were made.

We desperately needed documentation for our deep link design, so that it can be more easily used by any platform wishing to interact with Firefly.

Changelog

- Add deep link specification
- Add images of some UI (for new doc)

Relevant Issues

Please list any related issues using development keywords.

Closes #4872

Testing

Platforms

Please select any platforms where your changes have been tested.

• Desktop
  • MacOS
  • Linux
  • Windows
• Mobile
  • iOS
  • Android

Instructions

Please describe the specific instructions, configurations, and/or test cases necessary to test and verify that your changes work as intended.

1. Checkout this branch (chore/deep-link-documentation-for-registering-events)
2. Run yarn docs:start in the root directory of the repository

Checklist

Please tick all of the following boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or modified tests that prove my changes work as intended
• I have verified that new and existing unit tests pass locally with my changes
• I have verified that my latest changes pass CI workflows for testing and linting
• I have made corresponding changes to the documentation

[Tuditi]

Great work! 🥳

[Tuditi]

LGTM! 🔥