handle newlines in docs generation for exported fields

[arichardet]

Doc extraction for handling newlines in comments for exported fields results in creating a bullet for each newline. We should handle this in extract.go.

Here is sample output for file.fetch:

Exported Fields#
Here are the fields that are exported for use with ‘lookup’. Re-exported fields will have their own fields exported under the re-exported namespace.
> source (string) Source is the location of the file to fetch
> destination (string) Destination for the fetched file
> hash_type (string) HashType is the hash function used to generate the checksum hash
> hash (string) Hash is the checksum hash
> force (bool) Force indicates whether the file will be fetched if it already exists If true, the file will be fetched if:
> no checksum is provided
> the checksum of the existing file differs from the checksum provided