Tweak changelog note

Author: adamchainz

CHANGELOG.rst

@@ -8,7 +8,7 @@ Changelog
 
 * Expand Markdown detection to all Python language names from Pygments: ``py``, ``sage``, ``python3``, ``py3``, and ``numpy``.
 
-* Preserve leading blank lines with whitespace in reStructuredText code blocks.
+* Preserve leading whitespace lines in reStructuredText code blocks.
 
   Thanks to Julianus Pfeuffer for the report in `Issue #217 <https://github.com/adamchainz/blacken-docs/issues/217>`__.