chore(doc): added new instructions for e2e test with different lxd versions [WD-9034]

[mas-who]

Done

• Added some context in ARCHITECTURE.md about multi lxd version support in the UI
• Updated instructions in HACKING.md for running e2e tests for stable and edge lxd versions

QA

1. Run the LXD-UI:
   • On the demo server via the link posted by @webteam-app below. This is only available for PRs created by collaborators of the repo. Ask @mas-who or @edlerd for access.
   • With a local copy of this branch, run as described here.
2. Perform the following QA steps:
   • Check if updates in docs is clear.

[webteam-app]

Demo starting at https://lxd-ui-666.demos.haus

[edlerd]

Maybe suggest to use latest/edge here, so the next command below test-e2e-edge is connected?

[edlerd]

I was hoping we could describe how the test workflow is architected. Especially the matrix with channels and browsers. Also, how they are configured in pr.yaml and the connection to the projects in playwright.config.ts. Furthermore how the lxdVersion appears in the end to end tests and how it is used to enable / disable specific tests.

So instead of explaining why multiple version are there, explain how the different moving parts are working, and where they connect. Especially how they are configured, so we have a reference for future changes to the config.

[mas-who]

Aaaah sorry I misunderstood the assignment, will get that done 👍

[mas-who]

I realised one thing, it is not easy to write documentation 😅 I hope the updated text makes sense

[edlerd]

This is great, thanks! some suggestions below, address them or keep as is -- up to you :)