[docs] TypeScript withEnvironment: add ExternalServiceResource to union type example

[aspire-repo-bot]

Documents changes from microsoft/aspire#17393 by @maddymontaquila.

Targeting release/13.4 based on the source PR milestone 13.4 (exact match on microsoft/aspire.dev).

Why this PR is needed

Aspire 13.4 extended the TypeScript withEnvironment dispatcher to accept IResourceBuilder<ExternalServiceResource> as a value, matching the long-standing C# WithEnvironment(name, externalService) overload. Previously the generated TypeScript union omitted ExternalServiceResource, causing type-checking failures when users tried to pass an external service resource. For example, this pattern now works:

const externalSvc = await builder.addExternalService("api", "(api.example.com/redacted)
builder.addViteApp("web", "./web")
    .withEnvironment("VITE_API_URL", externalSvc);

The documentation's Union types section showed the withEnvironment example without ExternalServiceResource in the [AspireUnion] declaration. This PR corrects that example.

Changes

• Updated src/frontend/src/content/docs/extensibility/multi-language-integration-authoring.mdx — added IResourceBuilder<ExternalServiceResource> to the [AspireUnion] example in the Union types section.

Files modified

• src/frontend/src/content/docs/extensibility/multi-language-integration-authoring.mdx (updated)

Generated by PR Documentation Check for issue #17393 · ● 82.7M · ◷

[Copilot]

Pull request overview

Updates the integration authoring documentation to reflect Aspire 13.4’s expanded TypeScript withEnvironment union support by including IResourceBuilder<ExternalServiceResource> in the [AspireUnion] example.

Changes:

• Added typeof(IResourceBuilder<ExternalServiceResource>) to the [AspireUnion] declaration in the Union types documentation example.

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