Document change.move config parameter

This config parameter allows to disable the Move Change REST endpoint.
It was added in change I26466e359 and was meant as a temporary measure
until we decide how to solve the issues with the move change
functionality (in particular issue 9877). However so far we didn't
follow up on this, hence we should better document this setting while
it's there and being used.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I4194c55800c4ef5c48b2ffc9bd6988baedcba89c
diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index f51fdd1..21f7074 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -1240,6 +1240,23 @@
 +
 By default 1000.
 
+[[change.move]]change.move::
++
+Whether the link:rest-api-changes.html#move-change[Move Change] REST
+endpoint is enabled.
++
+The move change functionality has some corner cases with undesired side
+effects. Hence administrators may decide to disable this functionality.
+In particular, if a change that has dependencies on other changes is
+moved to a new branch, and the moved change gets submitted to the new
+branch, the changes on which the change depends are silently merged
+into the new branch, although these changes have not been moved to that
+branch (see details in
+link:https://bugs.chromium.org/p/gerrit/issues/detail?id=9877[issue
+9877]).
++
+By default true.
+
 [[change.replyLabel]]change.replyLabel::
 +
 Label name for the reply button. In the user interface an ellipsis (…)