fix(docs): remove duplicate entries in SUMMARY.md

The Architecture section contained three entries that were duplicates
of entries in the Reference section, causing mdBook to fail:
- create-module-bootstrap.md (also in Reference)
- kcsdk-python.md (also in C++ API Reference)
- kcsolve-python.md (also in C++ API Reference)

Remove the Architecture section entirely since all its entries exist
in their proper Reference sections.

docs/src/SUMMARY.md

@@ -13,12 +13,6 @@
   - [Silo](./guide/silo.md)
   - [Document Templates](./guide/templates.md)
 
-# Architecture
-
-- [Bootstrap and Addon Loading](./reference/create-module-bootstrap.md)
-- [KCSDK C++ Layer](./reference/kcsdk-python.md)
-- [KCSolve: Pluggable Solver](./reference/kcsolve-python.md)
-
 # Development
 
 - [Contributing](./development/contributing.md)