Update _sidebar redo

_sidebar.md

@@ -1,18 +1,18 @@
-[Home](Home)
-[Vision document](Vision Document)
-Requirements
-- [Use-Case Diagram](Use-Case Diagram)
-- [Use-Cases](Use-Cases)
-- [Domain Model](Domain Model)
-- [Sequence Diagrams](Sequence Diagrams)
-- [Wireframe](Wireframe)
-- [Usability Tests](Usability Test)
-- [Universal Design](Universal Design)
-System
-- [Project Structure](Project Structure)
-- [Class Diagram](Class Diagram)
-- [Persistence](Persistence)
-- [Source Code](Source Code)
-- [Installation Manual](Installation Manual)
-- [User Manual](User Manual)
-- [Testing](Testing)
+- [Home](Home)
+- [Vision document](Vision Document)
+- Requirements
+  - [Use-Case Diagram](Use-Case Diagram)
+  - [Use-Cases](Use-Cases)
+  - [Domain Model](Domain Model)
+  - [Sequence Diagrams](Sequence Diagrams)
+  - [Wireframe](Wireframe)
+  - [Usability Tests](Usability Test)
+  - [Universal Design](Universal Design)
+- System
+  - [Project Structure](Project Structure)
+  - [Class Diagram](Class Diagram)
+  - [Persistence](Persistence)
+  - [Source Code](Source Code)
+  - [Installation Manual](Installation Manual)
+  - [User Manual](User Manual)
+  - [Testing](Testing)