[network] Enable resolvconf service

When resolv.conf contained "search" keyword with no arguments
host/nslookup/dig utilities failed to parse it correctly.
This happens on systems with disabled resolvconf service and
gateway defined on any interface.

Change-Id: I6b95d038562eb457a856bba6104b7dbf9cc97d52
Closes-Bug: PROD-25927
(cherry picked from commit 95bc83afbb2567c5dca9f806ce289f2d1dc7e69f)
diff --git a/README.rst b/README.rst
index 4efa5e2..9655d5e 100644
--- a/README.rst
+++ b/README.rst
@@ -1829,7 +1829,7 @@
             - node2.domain.com
             - service2.domain.com
 
-Set up ``resolv.conf``, nameservers, domain and search domains:
+Set up ``resolvconf's basic resolver info``, e.g. nameservers, search/domain and options:
 
 .. code-block:: yaml
 
@@ -1837,16 +1837,16 @@
       network:
         resolv:
           dns:
-          - 8.8.4.4
-          - 8.8.8.8
+            - 8.8.4.4
+            - 8.8.8.8
           domain: my.example.com
           search:
-          - my.example.com
-          - example.com
+            - my.example.com
+            - example.com
           options:
-          - ndots: 5
-          - timeout: 2
-          - attempts: 2
+            - ndots:5
+            - timeout:2
+            - attempts:2
 
 Set up custom TX queue length for tap interfaces: