Fix "path to upload rights" diagram

[s-makin]

Description

The diagram on the path-to-upload-rights.md page was not rendering correctly and many of the labels had disappeared. After trying and failing several methods to fix the rendering, I decided to break up the diagram - which has the advantage that we can now link to the relevant parts of the diagram from other pages.

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Checklist

• I have read and followed the Ubuntu Project contributing guide
• My pull request is linked to an existing issue (if applicable)
• I have tested my changes, and they work as expected

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Additional notes (optional)

I think the changes I've made still reflect the spirit of the original - please let me know if that's not the case

[s-makin]

@cpaelzer since you were the originator of the diagram in the UMH, I'd like to get your +1 as well if possible that this still represents the spirit of the original

[cpaelzer]

Much better already @s-makin - thank you for the discussion. It might be hard to do, but the conversion from my hand drawing to a graph has one miss ... I intentionally shifted the rights half a block right to the skill.
So PPU and Package Set is somewhere between intermediate and Advanced (depending on what they apply) and so on.
Not sure if that is doable in the diagram, I can live with it but want to avoid anyone ever saying "but I apply for X and you ask for a skill from the next box". It sadly isn't that easy and depends a lot what exactly they apply for.

[s-makin]

Much better already @s-makin - thank you for the discussion. It might be hard to do, but the conversion from my hand drawing to a graph has one miss ... I intentionally shifted the rights half a block right to the skill. So PPU and Package Set is somewhere between intermediate and Advanced (depending on what they apply) and so on. Not sure if that is doable in the diagram, I can live with it but want to avoid anyone ever saying "but I apply for X and you ask for a skill from the next box". It sadly isn't that easy and depends a lot what exactly they apply for.

I'll see what I can do - glad to hear I'm on the right lines :)