title: Pass Swagger-UI url in drf-spectacular settings
body: <p>I have a project written in <code>Django 2.x.</code> I want to add automatic documentation to it using <strong>drf-spectacular</strong>. I'm using <code>drf-spectacular=0.15.1</code> at the moment.</p>
  <p>I'm running my project in Docker, and the build context for my api container is set as the root folder of the api project.</p>
  <p>When I run the command to generate the schema, <code>./manage.py spectacular --file schema.yml</code>, the script creates a <code>schema.yml</code> file in the root of my api project, but my Django <code>settings.py</code> are found one level below, in a folder called <code>my_website</code>. The structure of the project is like this:</p>
  <pre><code>main-project
  \api
   \_my_website
    __init__.py
    apps.py
    settings.py
    urls.py
  
   schema.yml
  
  \client
  docker-compose.yml
  </code></pre>
  <p>So in <code>settings.py</code> I added specific settings to tell Swagger-UI where from to take the schema, as specified in the <code>drf-spectacular</code> documentation:</p>
  <pre><code>SPECTACULAR_SETTINGS = {
      'SWAGGER_UI_SETTINGS': {
          'url': 'schema.yml'
      },
  }
  </code></pre>
  <p>Once I try to access the swagger-ui url in my project to check that the schema is loaded there, I get the error: <code>**Fetch error** Not Found schema.yml</code>. I tried passing the schema url in various ways, for example through relative url <code>../schema.yml</code> but that didn't work either. Maybe somebody can give me an idea of what I'm doing wrong.</p>
  <p>Thanks!</p>