Update README Repository Structure and document SSOT_Compiler.py

[fkhb90]

The 'Repository Structure' section in the README lists rules/, examples/, and docs/, but the actual repository contains:

SSOT_Compiler.py
URL-Ultimate-Filter-Surge.js
URL-Ultimate-Filter-Tampermonkey.user.js
docs/

Task

• Update the Repository Structure section to reflect the real files
• Add a short 'Build' subsection explaining what SSOT_Compiler.py does and how to run it to regenerate the Surge / Tampermonkey outputs from the single source of truth

This makes it much easier for a first-time contributor to understand the project layout. Good first issue — docs only.