Improve Operators Documentation Page

### Description

> This is an issue that is reserved for the Airflow Summit "Contributors" Workshop. This is denoted with the label `contributors-workshop`. Out of respect for the organizers and participants of this workshop, **please do not implement a PR that addresses this issue.**
>
> If this issue is still open following Airflow Summit, the label will be removed and the issue can be picked up.

There are a couple of areas where the Operators documentation can be improved:

- Handful of typos/capitalization issues (at least one under `Reserved params keyword`)
- Link to pre/post-execute documentation or include enhanced docs

Link to docs: https://airflow.apache.org/docs/apache-airflow/stable/core-concepts/operators.html

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)