Add the list of supported consumers and producers

[bobvanluijt]

Allows people to find the actually supported formats.

[casualjim]

Thanks but changing the html will make the change not persistent.
Also I think the links should use a commit hash otherwise they will start to point the the wrong location in the file as it gets changed.
Better chance of keeping the change around:
https://github.com/go-swagger/go-swagger/tree/master/docs

[bobvanluijt]

Thanks @casualjim

I've changed it and created a new pull request: go-swagger/go-swagger#1023