Clarify that `.m.rule.master` has a higher priority than any push rule

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

content/client-server-api/modules/push.md

@@ -368,18 +368,21 @@ Parameters:
 
 ##### Predefined Rules
 
-Homeservers can specify "server-default rules" which operate at a lower
+Homeservers can specify "server-default rules". They operate at a lower
-priority than "user-defined rules". The `rule_id` for all server-default
+priority than "user-defined rules", except for the `.m.rule.master` rule
-rules MUST start with a dot (".") to identify them as "server-default".
+which has always a higher priority than any other rule. The `rule_id`
-The following server-default rules are specified:
+for all server-default rules MUST start with a dot (".") to identify
+them as "server-default". The following server-default rules are
+specified:
 
 ###### Default Override Rules
 
 **`.m.rule.master`**
 
 Matches all events. This can be enabled to turn off all push
-notifications other than those generated by override rules set by the
+notifications. Unlike other server-default rules, this one has always a
-user. By default this rule is disabled.
+higher priority than other rules, even user defined ones. By default this
+rule is disabled.
 
 Definition: