docs: add more meat to the development section

[CommanderStorm]

This PR tries to add more meat to the devlopment seciton

Looks like much changed, actually is not.

Here is how the two details blocks look rendered

Content wise, some of the explainations are inspired by http://gist.github.com/nyurik/4e299ad832fd2dd43d2b27191ed3ec30/

[nyurik]

I added a few minor things, but looks great! Feel free to merge once resolved

[sharkAndshark]

Looks great! Just some small suggestions.

[Copilot]

Pull Request Overview

This PR enhances the documentation by adding clarifying details on development workflows and expanding the feature list for using Martin as a library. Key changes include:

• Updating the feature list in the Martin-as-a-library documentation with new bullet points and nested lists.
• Adding a comprehensive "Development" guide that details git setup, contribution instructions, and tool installation.
• Introducing a new README to facilitate local documentation building and link checking.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
docs/src/martin-as-a-library.md	Expanded feature list with new options and nested bullet formatting
docs/src/development.md	Revised and extended instructions for git setup and contributing new code
docs/README.md	Added guidance for building and previewing documentation locally

Comments suppressed due to low confidence (2)

docs/src/martin-as-a-library.md:7

• [nitpick] Consider using a consistent formatting style for feature names across all bullet points (e.g., inline code versus bold). Aligning the style helps maintain a clear and uniform presentation.

  * `mbtiles` - enable MBTile tile sources

docs/README.md:23

• Verify that the linked path src/SUMMARY.md correctly reflects the actual file location in the repository; if it resides elsewhere (for example, in docs/src), update the reference accordingly to avoid broken links.

> Make sure that all pages are linked from [`src/SUMMARY.md`](src/SUMMARY.md).

[nyurik]

thanks!