Fix typo in image-classification/README.md
Fix link typo of the following content.
PyTorch version, Trainer
PyTorch version, no Trainer

# What does this PR do?
Fixes a typo

## Who can review?
@sgugger @NielsRogge 
Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.


_The documentation is not available anymore as the PR was closed or merged._