Python extractor change notes: Rephrase for clarity.

Author: markshannon

change-notes/1.21/analysis-python.md

@@ -19,11 +19,12 @@
 
 ## Changes to code extraction
 
-* The extractor now exits gracefully if passed a non-existent file or directory either as a `--path` option or as a file name.
+* String literals as expressions within literal string interpolation (f-strings) are now handled correctly.
 
-* The extractor now exits gracefully if an invalid number was given as the `--max-procs` option.
+* The Python extractor now handles invalid input more robustly. In particular, it exits gracefully when:
 
-* String literals as expressions within literal string interpolation (f-strings) are now handled correctly.
+    * A non-existent file or directory is specified using the `--path` option, or as a file name.
+    * An invalid number is specified for the `--max-procs` option.
 
 
 ## Changes to QL libraries