Recommend --user-data-dir instead of CHROME_USER_DATA_DIR

test/data/import/brave-browser-laptop/README

@@ -2,8 +2,8 @@ Since Brave browser-laptop is based on Chromium (via Muon/Electron), most of the
 
 # Generating test data
 
-Unlike Chrome/Chromium, Brave browser-laptop does not support multiple profiles, so if you use Brave as your regular web browser, it may not be immediately obvious how you can create a separate profile for the purpose of generating test data. I found the least obtrusive method to be setting the CHROME_USER_DATA_DIR environment variable, e.g. on macOS:
+Unlike Chrome/Chromium, Brave browser-laptop does not support multiple profiles, so if you use Brave as your regular web browser, it may not be immediately obvious how you can create a separate profile for the purpose of generating test data. You can specify a custom user data directory with the `--user-data-dir` flag, e.g on macOS:
 
     TEST_UDD=/path/to/test/user/data/dir
     mkdir -p $TEST_UDD
-    CHROME_USER_DATA_DIR=$TEST_UDD /Applications/Brave.app/Contents/MacOS/Brave
+    /Applications/Brave.app/Contents/MacOS/Brave --user-data-dir=$TEST_UDD