Multiple projects DocFX structure

docfx.json

{
  "metadata": [
    {
      "src": [
        {
          "files": "src/ProjectA/**.cs",
          "exclude": [
            "**/obj/**",
            "**/bin/**"
          ],
          "src": ".."
        }
      ],
      "dest": "api/ProjectA"
    },
    {
      "src": [
        {
          "files": "src/ProjectB/**.cs",
          "exclude": [
            "**/obj/**",
            "**/bin/**"
          ],
          "src": ".."
        }
      ],
      "dest": "api/ProjectB"
    }
  ],
  "build": {
    "content": [
      {
        "files": [
          "api/**.yml",
          "api/**/index.md"
        ]
      },
      {
        "files": [
          "articles/**.md",
          "articles/**/toc.yml",
          "toc.yml",
          "*.md"
        ],
        "exclude": [
          "obj/**",
          "bin/**"
        ]
      }
    ],
    "resource": [
      {
        "files": [
          "images/**"
        ],
        "exclude": [
          "obj/**"
        ]
      }
    ],
    "overwrite": [
      {
        "files": [
          "apidoc/**.md"
        ],
        "exclude": [
          "obj/**"
        ]
      }
    ],
    "dest": "_site",
    "globalMetadataFiles": [],
    "fileMetadataFiles": [],
    "template": [
      "default"
    ],
    "postProcessors": [],
    "noLangKeyword": false
  }
}

Folder structure

+-- doc
⁞   +-- api
⁞   ⁞   +-- ProjectA
⁞   ⁞   ⁞   +-- index.md
⁞   ⁞   +-- ProjectB
⁞   ⁞       +-- index.md
⁞   +-- docfx.json
⁞   +-- toc.yml
+-- src
    +-- ProjectA
    +-- ProjectB

toc.yml

- name: Welcome
  href: articles/
- name: Project A
  href: api/ProjectA
  homepage: api/ProjectA/index.md
- name: Project B
  href: api/ProjectB
  homepage: api/ProjectB/index.md