types without any methods will generate broken markdown

[dustmop]

  outline: dataframe
    dataframe description
    path: dataframe

    functions:
      DataFrame(data) DataFrame
        constructs a DataFrame containing the given data
        params:
          data any
            data for the content of the DataFrame. Can be a list, dict, Series, or another DataFrame

    types:
      DataFrame
        a dataframe
        methods:
          d()
            d method

      GroupByResult
        result of a group_by call

      AtIndexer
        result of using the at attribute

Here both GroupByResult and AtIndexer have no methods. The generated markdown for the "Types" section looks like this:

## Types

### 'AtIndexer'

result of using the at attribute### 'DataFrame'

a dataframe### 'GroupByResult'

result of a group_by call

[b5]

hmm... we can definitely fix the template within outline, but we're using a different template for the qri docs site, correct? If so we'll have to fix this in that template as well