Improve generated docs

[kggilmer]

Documentation is generated for the model but we are currently leaving in any inline HTML markup.

We should consider stripping this or converting to markdown.
UPDATE: 2/25/2021 - some of this may have been handled in PR 61. We should still look into our generated documentation to figure out what improvements could be made. We should also process the HTML rather than just strip it (e.g. turn lists into markdown lists, links into proper links, perhaps even attempt to do inter doc linking).

I noticed in Intellij at least that the type hints don't show the documentation when the HTML tags are present:

 /**
     * <p>Lists the clients that have been created for the specified user pool.</p>
     */
    suspend fun listUserPoolClients(input: ListUserPoolClientsRequest): ListUserPoolClientsResponse

We should also probably generate documentation on the DslBuidler, FluentBuilder, and the immutable type itself when generating structures. Right now we only generate it on the immutable type but this doesn't help customers when building an object figure out what those properties are.

internal id: 176378957

[kggilmer]

(Aaron Todd - Jan 6, 2021)

[aajtodd]

this might be a duplicate of #136 at this point

[aajtodd]

closing as duplicate