User guide: Explain when self approvals are ignored

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Ieba85c7a521f92c08f8571722c1c6f82d5e099f3

resources/Documentation/user-guide.md

diff --git a/resources/Documentation/user-guide.md b/resources/Documentation/user-guide.md
index 29a3b37..70dfaeb 100644
--- a/resources/Documentation/user-guide.md
+++ b/resources/Documentation/user-guide.md
@@ -97,6 +97,11 @@
 that votes are sticky across patch sets, then also the code owner approvals
 which are based on these votes will be sticky.
 
+**NOTE:** Whether code owners can approve their own changes depends of the
+definition of the required label. If the label definition has
+[ignoreSelfApproval](../../../Documentation/config-labels.html#label_ignoreSelfApproval)
+enabled, code owner approvals of the patch set uploader are ignored.
+
 ## <a id="codeOwnerOverride">Code owner override
 
 Usually some privileged users, such as sheriffs, are allowed to override the