Adding changes to asr documentation
[🤖]: Hi @Ssofja 👋,

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/12351033732) for this PR just finished successfully

So it might be time to merge this PR or get some approvals

I'm just a bot so I'll leave it you what to do next.

//cc @pablo-garay @ko3n1g
# What does this PR do ?

In this PR ASR documentation fixes have added and outdated data was removed.
**Collection**: docs/asr
  
**PR Type**:
- [ ] New Feature
- [ ] Bugfix
- [x] Documentation