title: Configure conda build to exclude some folders from the conda package output
body: <h1>tl;dr:</h1>
  <p>How do you exclude folders from being packaged by <code>conda build</code> ?</p>
  <h1>Context</h1>
  <p>I am building my first packages with <code>conda build</code>.</p>
  <p>My meta.yaml file looks like this:</p>
  <pre><code>package:
      name: 'some_name'
      version: {{ load_setup_py_data().get('version') }}
  
  source:
      path: ./
  
  build:
      script: python setup.py install --single-version-externally-managed --record=record.txt
  
  requirements:
      run:
          - python &gt;=3.6
          - pandas &gt;=0.2
          - numpy &gt;=1.12
          # Packages that must be installed
          # in the user's conda environment
          # to run this package.
  
      build:
          # Packages used by setup.py
          # to install this package.
          # May also install compilers
          # for non-python code.
          - python
          - setuptools
  </code></pre>
  <p>And my root directory (where lies the setup.py &amp; meta.yaml files) looks like this:</p>
  <pre><code>$ ls
  README.md   __pycache__      input       isi_classif meta.yaml   
  notebooks   output      scripts     setup.py    version.py
  </code></pre>
  <p>Some folders are only there because they were useful during the prototyping but I don't want to delete them from the repo.</p>
  <p><em>How do I exclude a folder (like <code>input</code> or <code>notebooks</code> here) and its content from the package that conda builds ?</em></p>
  <p>For info, I build with the following command:</p>
  <pre><code>$ conda build some_folder_name
  </code></pre>