doc: group pretty-format.txt placeholders descriptions

diff --git a/Documentation/merge-config.txt b/Documentation/merge-config.txt
index 662c2713cab4b9762dded702897d9e92ee0a0549..a7f4ea90c11ff6092e77057bd5bee241499cf40f 100644 (file)
--- a/Documentation/merge-config.txt
+++ b/Documentation/merge-config.txt
@@ -63,6 +63,12 @@ merge.tool::
        Any other value is treated as a custom merge tool and requires
        that a corresponding mergetool.<tool>.cmd variable is defined.
 
+merge.guitool::
+       Controls which merge tool is used by linkgit:git-mergetool[1] when the
+       -g/--gui flag is specified. The list below shows the valid built-in values.
+       Any other value is treated as a custom merge tool and requires that a
+       corresponding mergetool.<guitool>.cmd variable is defined.
+
 include::mergetools-merge.txt[]
 
 merge.verbosity::