enable proof_minimal_theme

Author: mmcky

lectures/_config.yml

@@ -120,6 +120,9 @@ sphinx:
       schelling:     https://intro.quantecon.org/schelling.html
       scalar_dynam:  https://intro.quantecon.org/scalar_dynam.html
       complex_and_trig: https://intro.quantecon.org/complex_and_trig.html
+    # sphinx-proof
+    proof_minimal_theme: true
+    # sphinx-tojupyter
     tojupyter_static_file_path: ["source/_static", "_static"]
     tojupyter_target_html: true
     tojupyter_urlpath: "https://python.quantecon.org/"