Update change log link in README.md

Author: dbader

README.md

@@ -48,7 +48,7 @@ of the distribution or the project website at <https://Python-Markdown.github.io
 [installation]: https://python-markdown.github.io/install/
 [usage]: https://python-markdown.github.io/reference/
 
-See the change log at <https://Python-Markdown.github.io/change_log>.
+See the change log at <https://python-markdown.github.io/changelog/>.
 
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