docs: Add an example index

[ssheng]

What does this PR address?

Add an example index showcasing their frameworks, models, and additional functionality for easy search and discovery.

Before submitting:

• Does the Pull Request follow Conventional Commits specification naming? Here are GitHub's
  guide on how to create a pull request.
• Does the code follow BentoML's code style, both make format and make lint script have passed (instructions)?
• Did you read through contribution guidelines and follow development guidelines?
• Did your changes require updates to the documentation? Have you updated
  those accordingly? Here are documentation guidelines and tips on writting docs.
• Did you write tests to cover your changes?

[codecov]

Codecov Report

Merging #3551 (d1837a1) into main (9a6dc93) will decrease coverage by 0.06%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3551      +/-   ##
==========================================
- Coverage   31.68%   31.62%   -0.06%     
==========================================
  Files         138      138              
  Lines       11266    11287      +21     
  Branches     1856     1865       +9     
==========================================
  Hits         3570     3570              
- Misses       7453     7471      +18     
- Partials      243      246       +3     

Impacted Files	Coverage Δ
src/bentoml/bentos.py	43.07% <0.00%> (-2.83%)	⬇️
src/bentoml/_internal/container/__init__.py	76.23% <0.00%> (-1.77%)	⬇️
src/bentoml/container.py	67.50% <0.00%> (-0.80%)	⬇️
src/bentoml/_internal/bento/build_config.py	54.85% <0.00%> (-0.29%)	⬇️
src/bentoml/client.py	0.00% <0.00%> (ø)
src/bentoml/metrics.py	69.23% <0.00%> (ø)
src/bentoml/_internal/batch/spark.py	0.00% <0.00%> (ø)
src/bentoml/_internal/models/model.py	77.59% <0.00%> (ø)
src/bentoml/_internal/server/server.py	0.00% <0.00%> (ø)
src/bentoml/_internal/io_descriptors/json.py	38.55% <0.00%> (ø)
... and 4 more