Introducing rule ID numbers for validator rules

[dayantur]

This issue proposes associating each rule in the validator documentation (currently a work in progress in PR #851) with a unique rule ID.

This rule ID will also be:

• documented in the detailed documentation
• referenced consistently in the validation report

This approach serves three main purposes:

• help users understand what is checked and what is not
• provide a clear way to look up additional information about a specific rule
• provide a clear and unambiguous reference when reporting bugs or issues