Add ansible 2.5 release note

It's added to an existing file so that it will appear in the 3.1.0 section.

The overridable matcher note is changed to an upgrade note since it may
require changes.

And tidy up some other notes.

Change-Id: Ib049679f7df4424e43508a96096acecc6722f606

releasenotes/notes/driver-mqtt-28f62e8510863b40.yaml

@@ -1,3 +1,3 @@
 ---
 features:
-  - A :attr:<mqtt connection> driver is added to feature build report over MQTT message.
+  - A :attr:`<mqtt connection>` driver is added to feature build report over MQTT message.

releasenotes/notes/override-file-matchers-128731229d551d81.yaml

@@ -1,4 +1,4 @@
-features:
+upgrade:
   - |
     Files (and irrelevant-files) matchers are now overridable.  Zuul
     now uses only branch matchers to collect job variants.  Once those
@@ -6,3 +6,4 @@ features:
     irrelevant-files attributes are inherited and overridden as any
     other job attribute.  The final values are used to determine
     whether the job should ultimately run.
+  - Zuul now uses Ansible 2.5.

releasenotes/notes/role-in-json-4bc0d862066a4390.yaml

@@ -1,6 +1,5 @@
 ---
 features:
   - |
-    Add role name to json log
-    The json log contains now also the role name and the uuid
+    The json log now also contains the role name and the uuid
     similar to the task entry.