Update quantecon-book-theme to 0.18.0 and enable sticky_contents (#476)

- Bump quantecon-book-theme from 0.17.1 to 0.18.0
- Enable sticky_contents in html_theme_options for sticky RHS menu

Author: mmcky

environment.yml

@@ -7,7 +7,7 @@ dependencies:
   - pip
   - pip:
     - jupyter-book>=1.0.4post1,<2.0
-    - quantecon-book-theme==0.17.1
+    - quantecon-book-theme==0.18.0
     - sphinx-tojupyter==0.6.0
     - sphinxext-rediraffe==0.3.0
     - sphinx-exercise==1.2.1

lectures/_config.yml

@@ -52,6 +52,7 @@ sphinx:
       keywords: Python, QuantEcon, Quantitative Economics, Economics, Sloan, Alfred P. Sloan Foundation, Tom J. Sargent, John Stachurski
       analytics:
         google_analytics_id: G-X7DH1M2DPY
+      sticky_contents: true
       launch_buttons:
         notebook_interface        : classic  # The interface interactive links will activate ["classic", "jupyterlab"]
         colab_url                 : https://colab.research.google.com