Config guide: Document how to make approvals and overrides sticky

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I8cef263a45a71786a263e42450c0acd2b36e32b6

resources/Documentation/config-guide.md

diff --git a/resources/Documentation/config-guide.md b/resources/Documentation/config-guide.md
index 77f2d7f..3c9432b 100644
--- a/resources/Documentation/config-guide.md
+++ b/resources/Documentation/config-guide.md
@@ -20,6 +20,14 @@
 
 Some of the configuration parameters have an effect on the user workflow.
 
+### <a id="stickyApprovals">Make code owner approvals / overrides sticky
+
+Code owner approvals and code owner overrides can be made sticky by enabling
+[copy rules](../../../Documentation/config-labels.html#label_copyAnyScore) in
+the definitions of the labels that are configured as [required
+approval](config.html#pluginCodeOwnersRequiredApproval) and [override
+approval](config.html#pluginCodeOwnersOverrideApproval).
+
 ### <a id="implicitApprovals">Implicit code owner approvals
 
 It's possible to [enable implicit approvals](config.html#pluginCodeOwnersEnableImplicitApprovals)