--- a/mercurial/help/config.txt	Thu Jul 19 10:06:58 2018 +0200
+++ b/mercurial/help/config.txt	Thu Jul 19 10:35:29 2018 +0200
@@ -1773,6 +1773,20 @@
 
 Alias definitions for revsets. See :hg:`help revsets` for details.
 
+``revlog``
+----------
+
+Control the strategy Mercurial uses internally to store history. Options in this
+category impact performance and repository size.
+
+``optimize-delta-parent-choice``
+    When storing a merge revision, both parents will be equally considered as
+    a possible delta base. This results in better delta selection and improved
+    revlog compression. This option is enabled by default.
+
+    Turning this option off can result in large increase of repository size for
+    repository with many merges.
+
 ``server``
 ----------