Docs: Extended guidelines for presets, fields, deprecations

[tordans]

@tyrasd following our conversation on the last iD community call I created this draft of a separate document that outlines the decisions that guide adding presets, fields and so on.

I suggest we collect some feedback but the start using it which will be the best way to improve it over time.

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This is heavily inspired by https://github.com/streetcomplete/StreetComplete/blob/master/QUEST_GUIDELINES.md – thanks a lot

[github-actions]

🍱 You can preview the tagging presets of this pull request here.

[Asteliks]

I suggest enhancing the guidelines by recommending that new presets inherit fields from more commonly used presets. For example, when creating a specific shop type, inherit fields from the general shop preset and then add specific fields as needed. This ensures consistency, reduces redundancy, and simplifies maintenance. When the general preset is updated, the specific presets automatically inherit these updates, keeping everything current and consistent.

Additionally, it might be helpful to include best practices for testing new presets to ensure they function correctly within the tagging schema.

Other than that is all seems good to me.