[DOC] add missing torch entries in README and documentation

[Abhishek9639]

Description

Added the missing torch integration entries in the README feature table and created a full example page for TorchExperiment, following the pattern of existing sklearn/sktime integrations.

Related Issues

Fixes #211

Type of Change

• [DOC] - Documentation changes

How was this solved?

• Added torch entry to the integrations table in examples/integrations/README.md
• Created torch_experiment_example.py with a working example using TorchExperiment+ HillClimbing optimizer
• Added a "PyTorch Lightning Integration" section in the Sphinx docs (docs/source/examples/integrations.rst)
• Updated the README feature table's third column to "Problems & Experiments" as suggested in the issue

Checklist

• PR title includes appropriate tag: [BUG], [ENH], [DOC] or [MNT]
• Linked to related issue (if applicable)
• Code passes make check (lint, format, isort)
• Tests added/updated for changes (if applicable)
• Documentation updated (if applicable)

Testing

The new example is auto-discovered by examples/test_examples.py and passes.

[Abhishek9639]

Hii @SimonBlanke,
this is ready for review! I've added the missing torch entries as discussed in #211 added the TorchExperiment to the integrations table, created a full example page, updated the docs, and renamed the third column in the feature table. Let me know if anything needs changes.

[SimonBlanke]

@Abhishek9639 Thanks for opening the PR.
The Issue is from a time where the readme looked like this:
https://github.com/hyperactive-project/Hyperactive/tree/2842478bb89325d13809aae7cb3dd44922d8de1c

This is very different (and worse) from now (the current main). So the suggestions made by @fkiraly should have raised some questions, right? It would have been good to task clarifications in the Issue itself.
Because of this the changes in the readme do not make sense. The pytorch integrations is already presented in the 'key features' in the current readme.

Remove your changes in both readmes.

The example and the changes in the docs make sense though. You can leave them.