Distributed Validator Flow doc

[corverroos]

🎯 Problem to be solved

We need to describe the distributed validator flow and how it differs from a normal validator flow (use it as reference).

🛠️ Proposed solution

• Add a Distributed Validator Flow page after the Charon Networking page.
• Reference the traditional validator flow doc and use a similar style.
• We might even duplicate that doc, and then add sections/highlights that show it differs.
• Also add a section for sync committees.