Improve the DeepSpeed page

Nobody has claimed this yet.

## 🐛 Bug

This page: https://pytorch-lightning.readthedocs.io/en/latest/api/pytorch_lightning.utilities.deepspeed.html is referenced directly by DeepSpeed docs.

We need to provide more useful information for folks clicking the link and discovering DeepSpeed from it.

### To Reproduce

### Expected behavior

### Environment

- PyTorch Lightning Version (e.g., 1.5.0):
- PyTorch Version (e.g., 1.10):
- Python version (e.g., 3.9):
- OS (e.g., Linux):
- CUDA/cuDNN version:
- GPU models and configuration:
- How you installed PyTorch (`conda`, `pip`, source):
- If compiling from source, the output of `torch.__config__.show()`:
- Any other relevant information:

### Additional context

cc @lantiga @borda @rohitgr7 @akihironitta

Start with the linked DeepSpeed API page and inspect how it is presented to someone arriving from the DeepSpeed documentation. Determine what useful information is missing; the work is done when the page provides clearer, more useful guidance for those visitors.

Written by the indexing model from the issue text.