📝 Add docs for virtual environments and environment variables, update contributing (#1082)

mkdocs.yml

@@ -71,6 +71,9 @@ nav:
     - learn/index.md
     - databases.md
     - db-to-code.md
+    - environment-variables.md
+    - virtual-environments.md
+    - install.md
     - Tutorial - User Guide:
       - tutorial/index.md
       - tutorial/create-db-and-table-with-db-browser.md