Update doc/devel/release_guide.rst

Co-Authored-By: Elliott Sales de Andrade <[email protected]>

Author: SidharthBansal

doc/devel/release_guide.rst

@@ -113,7 +113,7 @@ Similarly for the "API changes",
 
  1. copy the current api changes to a file is :file:`doc/api/prev_api_changes`
  2. merge all of the files in the most recent :file:`doc/api/api_changes_X.Y`
-    into :file:`doc//whats_new.rst`
+    into :file:`doc/api/api_changes.rst`
  3. comment out the most recent API changes at the top.
 
 In both cases step 3 will have to be un-done right after the release.