[Templates] Small fixes for 2.6

[justinvyu]

Why are these changes needed?

This PR updates the batch inference example content based on @angelinalg's feedback. This also remove the duplicate copy that was used for the workspace template. Now, only one copy of this example lives in doc/source/templates/01_batch_inferece/start.ipynb, and the one in doc/source/data/examples is just a symlink. The example uses absolute urls so that the links all work on Anyscale. The reason for this is that maintaining 2 versions is way too much overhead even on minor edits such as these.

For reviewers

Link to the updated content: https://anyscale-ray--36781.com.readthedocs.build/en/36781/data/examples/pytorch_resnet_batch_prediction.html

Main content changes:

• Adding a useful link at the beginning (to batchinference.io landing page)
• Fixing some typos - "map" API reference instead of "map_batches"
• Making things work out of the box if head node has no GPU (setting the device correctly instead of always moving to cuda)

Related issue number

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• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

[amogkam]

Thanks, changes look good to me. Unfortunately, this puts us in a catch-22 for the hyperlinks. If we link with latest, the master docs will be incorrect. If we link with master, then the release docs will be incorrect.

For 2.6, should we keep them as separate examples until we figure out a long term approach for consolidation?

[sofianhnaide]

Approving based on Amog