Docs: Clarify development setup prerequisites and Docker usage

[Sailnagale]

Hi maintainers ,

While going through the Development section as a first-time contributor,
I noticed that the setup instructions assume familiarity with Docker and
the make pypistats command, but do not clearly mention the required
prerequisites (Docker, Docker Compose, Make) or explain what the command does.

This can be a bit confusing for beginners setting up the project locally.

If this sounds useful, I would like to:

• Add a short "Prerequisites" subsection (Docker, Docker Compose, Make)
• Briefly explain what make pypistats does
• Add links to relevant installation documentation where appropriate

These changes would likely be in the main documentation files
(README.rst and/or related docs files).

Please let me know if this approach looks okay before I proceed.

Thanks!