Add unsafe-code/best-practices.md (#48557)

Author: EgorBo

docs/navigate/advanced-programming/toc.yml

@@ -418,6 +418,8 @@ items:
     href: ../../standard/managed-code.md
   - name: Automatic memory management
     href: ../../standard/automatic-memory-management.md
+  - name: Unsafe code best practices
+    href: ../../standard/unsafe-code/best-practices.md
   - name: Clean up unmanaged resources
     items:
     - name: Overview