Provide example data on definition properties

[danpetitt]

By decorating a definition property with an xml comment, you will get proper 'live' sample data in the example section of a response.

Hope this is okay, not done many PRs before :-)

[heldersepu]

Looks good, I like the idea!

And the <example> is not a new tag:
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/xmldoc/recommended-tags-for-documentation-comments

[danpetitt]

Yeah thats why i did it that way, as i saw it being emitted into the XMLComments; i was originally doing a custom attribute in my own OperationFilter and thought there may be a more native way to do this.

[jcharlesworthuk]

+1 For getting this merged

[hfurubotten]

+1 from me as well on this. Not only will this make it easier to get more rich information in the UI, but also improve documentation a lot for many. At least will it help the team im on here tremendously.

This might also help on the issue reported on #1137, which we also are experiencing on many of our apis, by doing this correctly natively.