fix: added endpoint to get the genesis block hash

[squirer]

Purpose

Add endpoint to get the genesis block hash for the connected network

Changes

Add endpoint, updated changelog and readme

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.