Make onboarding mappings more explicit.

[SilasBerger]

Status quo

Currently, the onboarding sync config mostly maps top-level folders:

- src: 04-accounts
  dst: 01-accounts
  ignore:
      - 02-mfa/01-wechsel-smartphone
- src: 05-tips/01-updates
  dst: 02-updates
- src: 02-software-communication
  dst: 03-software-communication

This works, but if one of these folders gets a new sub-page that doesn't belong in the onboarding (e.g. we add a section for a new piece of software), we always have to remember to explicitly ignore it.

Problem

Explicit mappings would (1) prevent this issue and (2) allow us to change how the documents are organized in the onboarding (e.g. pull the Office 365 section a level higher, out of the Software section):

- src: 04-accounts/01-schulkonto
  dst: 01-accounts/01-schulkonto
- src: 04-accounts/02-mfa
  dst: 01-accounts/02-mfa
  ignore:
      - 02-mfa/01-wechsel-smartphone
- src: 04-accounts/03-ausweisfoto
  dst: 01-accounts/03-ausweisfoto
- src: 05-tips/01-updates
  dst: 02-updates
- src: 02-software-communication/01-office
  dst: 03-office
- src: 02-software-communication/02-untis
  dst: 04-weitere-software/01-untis
- src: 02-software-communication/03-adobe
  dst: 04-weitere-software/02-adobe

The problem is that e.g. the 04-weitere-software section will get an auto-generated title of weitere-software in the sidebar, which we can't easily change.

Suggestion

• Create a new folder like docs/hidden.
• Make sure that this folder is ignored in the default autogenerated sidebar.
• Use this folder to create auxiliary files such as docs/hidden/weitere-software/_category_.json

We could then map these aux files into the onboarding file structure without having them show up in the default autogenerated sidebar:

(...)
- src: 02-software-communication/01-office
  dst: 03-office
- src: hidden/weitere-software/_category_.json
  dst: 04-weitere-software/_category_.json
- src: 02-software-communication/02-untis
  dst: 04-weitere-software/01-untis
- src: 02-software-communication/03-adobe
  dst: 04-weitere-software/02-adobe

[lebalz]

Good point. Whats about an extension of the sync mechanism which support's a "dst" + "action" + "data" key:

- dst: 04-weitere-software/_category_.yml
  action: create-or-override
  data:
  - label: Software

The action could be "create-or-override", "create" or possible for a follow up "transform-frontmatter" (which would apply the provided data to the frontmatter of the copied file, e.g. when the sidebar-label was set over the frontmatter).

The data field could potentially be an array of lines too, which then would be simply joined with newlines