fix dev-guide inclusion of fragment guide

Author: alvyjudy

docs/development/developer-guide.rst

@@ -68,7 +68,7 @@ intended to solve.
 All PRs with code changes should include tests. All changes should
 include a changelog entry.
 
-.. include:: ../changelog.d/README.rst
+.. include:: ../../changelog.d/README.rst
 
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