Add development guide to index.json

[turkenf]

Description of your changes

This PR adds the development guide to index.json

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable to ensure this PR is ready for review.
• [ ] Added backport release-x.y labels to auto-backport this PR if necessary.

[turkenf]

Thank you for reviewing @ulucinar, since we will no longer be maintaining the Monolithic package starting next month, I think there is no need.