Simple navigation created and file renamed.

Author: hreikin

docs/getting-started/installation-and-usage.md renamed to docs/getting-started/getting-started.md

@@ -72,4 +72,7 @@ markdown_extensions:
       alternate_style: true
   - pymdownx.tasklist:
       custom_checkbox: true
-  - pymdownx.tilde
+  - pymdownx.tilde
+nav:
+  - Home: 'index.md'
+  - Getting Started: 'getting-started/installation-and-usage.md'