Updates readme to use GitHub action status for badges (#776)

# Description

Earlier the README had hard-coded values for "passing" of pre-commit and
docs. This changes it to use the GitHub actions instead.

## Type of change

- This change requires a documentation update

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

README.md

@@ -8,8 +8,8 @@
 [![Python](https://img.shields.io/badge/python-3.10-blue.svg)](https://docs.python.org/3/whatsnew/3.10.html)
 [![Linux platform](https://img.shields.io/badge/platform-linux--64-orange.svg)](https://releases.ubuntu.com/20.04/)
 [![Windows platform](https://img.shields.io/badge/platform-windows--64-orange.svg)](https://www.microsoft.com/en-us/)
-[![pre-commit](https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit&logoColor=white)](https://pre-commit.com/)
-[![Docs status](https://img.shields.io/badge/docs-passing-brightgreen.svg)](https://isaac-sim.github.io/IsaacLab)
+[![pre-commit](https://img.shields.io/github/actions/workflow/status/isaac-sim/IsaacLab/pre-commit.yaml?logo=pre-commit&logoColor=white&label=pre-commit&color=brightgreen)](https://github.com/isaac-sim/IsaacLab/actions/workflows/pre-commit.yaml)
+[![docs status](https://img.shields.io/github/actions/workflow/status/isaac-sim/IsaacLab/docs.yaml?label=docs&color=brightgreen)](https://github.com/isaac-sim/IsaacLab/actions/workflows/docs.yaml)
 [![License](https://img.shields.io/badge/license-BSD--3-yellow.svg)](https://opensource.org/licenses/BSD-3-Clause)