chore: add plugin documentation

[eirikhaugstulen]

This PR adds the plugin developer documentation. This documentation will be hosted on the developers portal.

[eirikhaugstulen]

PR in the developers portal: dhis2/developer-portal#152

[simonadomnisoru]

Hey,
In the Github preview for the newly added files there are some syntaxes that are not displayed correctly (warnings, tips, images, etc.). I suggested some alternatives using regular markdown syntax, but I'm not sure if this is a cause for concern or if it will compile and display correctly in the developer portal.
Thanks!

[eirikhaugstulen]

Hey again! Thanks for the review @simonadomnisoru.

I actually ended up rewriting most of the documentation as it was not great. I'm aware that the preview functionality in GitHub does not really deal with mdx and docusaurus syntax very well, but you can inspect the final result here:
https://deploy-preview-152--dhis2-developer-portal.netlify.app/docs/capture-plugins/developer/getting-started

It does seem to be parsed and displayed correctly here! Please have a look and get back to me 👍

[simonadomnisoru]

Hey again! Thanks for the review @simonadomnisoru.

I actually ended up rewriting most of the documentation as it was not great. I'm aware that the preview functionality in GitHub does not really deal with mdx and docusaurus syntax very well, but you can inspect the final result here: https://deploy-preview-152--dhis2-developer-portal.netlify.app/docs/capture-plugins/developer/getting-started

It does seem to be parsed and displayed correctly here! Please have a look and get back to me 👍

The final result on the developers portal looks great! Good job 👏

[dhis2-bot]

🎉 This PR is included in version 100.69.3 🎉

The release is available on:

• AppHub release
• v100.69.3
• GitHub release

Your semantic-release bot 📦🚀