title: DocFX: Generate API documentation for multiple projects
body: <p>I'm working on a project that has multiple projects in a solution.  I would like to be able to generate the documentation from an outside directory to keep the application code folders clean.  When I try to set the src directory in my docfx.json, it doesn't seem to like absolute paths, nor does it like relative paths.</p>
  
  <pre><code>{
    "metadata": 
    [{
           "src": 
           [{
                 "files": ["../../../Repos/Wsi.Extranet.CommonServices/Wsi.Extranet.CommonServices/**/*.csproj"]
                 "exclude": 
                 [
                      "**/obj/**",
                      "**/bin/**",
                      "_site/**"
                 ]
          }],
          "dest": "api"
  }],
  "build": {
  "content": [
    {
      "files": [
        "api/**.yml",
        "api/index.md"
      ]
    },
    {
      "files": [
        "articles/**.md",
        "articles/**/toc.yml",
        "toc.yml",
        "*.md"
      ],
      "exclude": [
        "obj/**",
        "_site/**"
      ]
    }
  ],
  "resource": [
    {
      "files": [
        "images/**"
      ],
      "exclude": [
        "obj/**",
        "_site/**"
      ]
    }
  ],
  "overwrite": [
    {
      "files": [
        "apidoc/**.md"
      ],
      "exclude": [
        "obj/**",
        "_site/**"
      ]
    }
  ],
  "src":    "../../../Repos/Wsi.Extranet.CommonServices/Wsi.Extranet.CommonServices",
  "dest": "_site",
  "globalMetadataFiles": [],
  "fileMetadataFiles": [],
  "template": [
    "default"
  ],
  "postProcessors": [],
  "noLangKeyword": false
   }
  }
  </code></pre>
  
  <p>It says it built fine but didn't find any files and the directory that it searches for is staying in the current directory.</p>
  
  <pre><code>D:\temp\WsiApiDocs\docfx_project&gt;docfx metadata
  Info: Config file docfx.json found, start generating metadata...
  Info: No files are found with glob pattern **/*.csproj, excluding
      **/obj/**,**/bin/**,_site/**, under directory "D:\temp\WsiApiDocs\docfx_project"
  Info: Completed executing in 54.0087 milliseconds.
  
  
  Build succeeded.
      0 Warning(s)
      0 Error(s)
  </code></pre>
  
  <p>When I attempt to put the relative path in the files property, I get the following:</p>
  
  <pre><code>D:\temp\WsiApiDocs\docfx_project&gt;docfx metadata
  Info: Config file docfx.json found, start generating metadata...
  Info: No files are found with glob pattern
   ../../../Repos/Wsi.Extranet.CommonServices/Wsi.Extranet.CommonServices/**/*.csproj, 
  excluding **/obj/**,**/bin/**,_site/**, under directory
   "D:\temp\WsiApiDocs\docfx_project"
  **Warning: NOTE that `../` is currently not supported in glob pattern, please use `../` in `src` option instead.**
  Info: Completed executing in 48.9621 milliseconds.
  
  
  Build succeeded with warning.
  Warning: NOTE that `../` is currently not supported in glob pattern, please use `../` in `src` option instead.
      1 Warning(s)
      0 Error(s)
  </code></pre>
  
  <p>So my confusion seems to be in how to use the src option instead.  If use the src in metadata, then it seems that I can't specify the file and exclusion info.  I tried to use a src property on the same level as metadata but that seemed to do nothing.</p>