Clarify upgrade

Author: simonw

selenium/selenium-python-macos.md

@@ -10,17 +10,17 @@ This is by far the easiest option:
 
     brew install chromedriver --cask
 
-Or to upgrade an existing installation:
+This also ensures `chromedriver` is on your path, which means you don't need to use an explicit `chromedriver_path` later on.
 
-    brew upgrade chromedriver --cask
+You still need to run it once in the terminal `chromedriver` to get the macOS error, then allow it in the `Security & Privacy` preferences - see below.
 
-This is useful if you are seeing an error like this one:
+To upgrade an existing installation do this:
 
-> Message: session not created: This version of ChromeDriver only supports Chrome version 85
+    brew upgrade chromedriver --cask
 
-This also ensures `chromedriver` is on your path, which means you don't need to use an explicit `chromedriver_path` later on.
+Knowing how to upgrade an existing version is useful if you are seeing an error like this one:
 
-You still need to run it once in the terminal `chromedriver` to get the macOS error, then allow it in the `Security & Privacy` preferences - see below.
+> Message: session not created: This version of ChromeDriver only supports Chrome version 85
 
 ### Without using homebrew