Fixed typo (#2118)

Charles Fox, CFA · emmanuelle · commit d66e7719a639 · 2020-01-23T13:22:35.000-05:00
of -&gt; or
diff --git a/doc/python/v4-migration.md b/doc/python/v4-migration.md
@@ -52,7 +52,7 @@ To migrate version 3 "online" functionality, first install the `chart-studio` pa
 $ pip install chart-studio
 ```
 
-of conda.
+or conda.
 
 ```
 $ conda install -c plotly chart-studio
