book: remove unfinished sections

Author: BrettMayson

book/SUMMARY.md

@@ -60,13 +60,3 @@
   - [Config](lints/config.md)
   - [SQF](lints/sqf.md)
   - [Stringtables](lints/stringtables.md)
-
-<!--
-# Modding Guide
-
-- [Getting Started](getting-started/index.md)
-- [Project Structure](project-structure/index.md)
-    - [Prefixing](project-structure/prefixing.md)
-    - [Addons](project-structure/addons.md)
-    - [Optionals](project-structure/optionals.md)
- -->