minor edits

Author: LiamConnors

doc/python/selections.md

@@ -29,7 +29,7 @@ jupyter:
     name: Selections
     order: 26
     permalink: python/selections/
-    thumbnail: thumbnail/make_selection.png
+    thumbnail: thumbnail/make_selection.jpg
 ---
 
 ## Adding Selections

doc/python/setting-graph-size.md

@@ -128,7 +128,7 @@ fig.show()
 ```
 
 ### Automatically Adjust Specific Margins
-You can also set auto-margin for specific sides of the figure. Here, we set `automargin` on the `left` and `top` of the figure.
+You can also set `automargin` for specific sides of the figure. Here, we set `automargin` on the `left` and `top` of the figure.
 
 ```python
 import plotly.graph_objects as go