5232 Enhance bundle page with more information (#5234)

Fixes #5232 .

### Description

According to user's feedback, this PR enhanced the MONAI bundle doc page
to include tutorial examples and model-zoo info.

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

Signed-off-by: Nic Ma <nma@nvidia.com>

Author: Nic-Ma

docs/source/bundle_intro.rst

@@ -8,3 +8,7 @@ Bundle
 
    mb_specification
    config_syntax.md
+
+Detailed bundle examples and get started tutorial: https://github.com/Project-MONAI/tutorials/tree/main/bundle
+
+A collection of medical imaging models in the MONAI Bundle format: https://github.com/Project-MONAI/model-zoo