Fixed tiny mistake

mkdocs.yml

@@ -3,10 +3,10 @@ site_name: Python for Hackers - Quick Start
 nav:
   - home: index.md
   - 'Development Environment':
-    - 'TODO: Files and Directories (types, shebang)'
-    - 'TODO: Virtual Environments'
-    - 'TODO: Makefiles'
-    - 'TODO: Pip'
+    - 'TODO - Files and Directories (types, shebang)': ./
+    - 'TODO - Virtual Environments': ./
+    - 'TODO - Makefiles': ./
+    - 'TODO - Pip': ./
   - 'Values and Types': 'values-and-types/README.md'
   - 'Conditionals': 'conditionals/README.md'
   - 'Iteration':