[Documentation] Deduplicate docs on sample directory structure for REST API specs

[konrad-jamrozik]

See

• https://dev.azure.com/azure-sdk/internal/_git/azure-sdk-docs-eng.ms/pullRequest/796#1693263612
• https://dev.azure.com/azure-sdk/internal/_git/azure-sdk-docs-eng.ms/pullrequest/796
• Email thread with @raych1 Subject: RE: Azure Carbon Optimization Team's Pull Request in Private Repo missing the SDK artifacts and the API Views - What causes this and how to resolve?

Places to dedup:

• UPDATED https://github.com/Azure/azure-rest-api-specs/blob/main/README.md#directory-structure
• TYPESPEC-SPECIFIC https://github.com/Azure/azure-rest-api-specs/blob/main/documentation/typespec-structure-guidelines.md
• DELETED https://eng.ms/docs/products/azure-developer-experience/design/api-specs/api-dir-layout
• DELETED https://github.com/Azure/azure-rest-api-specs/wiki
• DEPRECATED https://dev.azure.com/azure-sdk/internal/_wiki/wikis/internal.wiki/902/API-spec-checking-in-and-PR-review?anchor=folder-structure-in-the-spec-repos

[konrad-jamrozik]

Closed as superseded by:

• Documentation: Deduplicate specs directory structure (folder layout) guidance #7628