Doc: Pacemaker Explained: document priority-fencing-delay cluster option

Author: gao-yan

doc/Pacemaker_Explained/en-US/Ch-Options.txt

@@ -292,6 +292,20 @@ are +stop+ to attempt to immediately stop pacemaker and stay stopped, or
 on failure. The default is likely to be changed to +panic+ in a future release.
 '(since 2.0.3)'
 
+| priority-fencing-delay  | |
+indexterm:[priority-fencing-delay,Cluster Option]
+indexterm:[Cluster,Option,priority-fencing-delay]
+Enforce specified delay for the fencings that are targeting the lost
+nodes with the highest total resource priority in case we don't
+have the majority of the nodes in our cluster partition, so that
+the more significant nodes potentially win any fencing match,
+which is especially meaningful under split-brain of 2-node
+cluster. If all the nodes have equal priority, then any
+pcmk_delay_base/max configured for the corresponding fencing
+resources will be applied. Otherwise as long as it's set, even if
+to 0, it takes precedence over any configured pcmk_delay_base/max.
+By default, priority fencing delay is disabled.
+
 | cluster-delay | 60s |
 indexterm:[cluster-delay,Cluster Option]
 indexterm:[Cluster,Option,cluster-delay]