Adding regime code page

[methodofaction]

Problem: we have a broken link at https://docs.gobl.org/draft-0/tax/regime_code. It seems this should be self generated, but it's not.

Tried to do this from the gobl repo, but Cursor was mangling everything and we couldn't figure out how to fix it elegantly. Instead, I'm manually generating the page and assigning a ticket in Linear for this to be fixed as it should.

[Copilot]

Pull request overview

Adds the missing RegimeCode documentation page so links to /draft-0/tax/regime_code resolve correctly in the published docs.

Changes:

• Added a new draft-0/tax/regime_code.mdx page documenting tax.RegimeCode and its supported values.
• Linked the new page into the Mintlify navigation via docs.json.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
draft-0/tax/regime_code.mdx	Introduces the missing RegimeCode schema page and enumerates supported regime identifiers.
docs.json	Adds the new page to the “Schemas (Draft 0) → Tax” navigation so it’s discoverable and not orphaned.

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[Copilot]

For consistency with other enum docs under ## Values (e.g. draft-0/l10n/tax_country_code.mdx, draft-0/currency/code.mdx), this table should use the same column headings (Value | Title | Description). Right now it uses Code | Country, which makes the generated docs inconsistent.