Rename `example` recipe to `example-v0`

[pavelzw]

General comment:

I think we should rename the example directory to example-v0. For new-joiners, it makes it clear which example is the old and which is the new version.

WDYT @conda-forge/staged-recipes?

[ocefpaf]

I wonder if we should just remove it and rename the other one to example. While I'd rather have grayskull supporitng v1 before doing that, I think that those doing v1 know what it is by now and we should try to get more people onboard.

[pavelzw]

also fine with me