Fix bsc#992742 recommend per-node maintenance mode

Title: "Should section 4.3 recommend per-node maintenance mode instead of
whole-cluster maintenance mode?"

Use "crm node" for putting a node into maintenance mode instead of the
whole cluster.

* Use crm node maintenance NODE = set node maintenance mode ON
* Use crm node ready NODE = set node maintenance mode OFF

xml/ha_migration.xml

@@ -626,8 +626,9 @@
    <para>
     Before starting an update for a node, either <emphasis>stop</emphasis>
     the cluster stack <emphasis>on that node</emphasis> or put the
-    <emphasis>cluster into maintenance mode</emphasis> (see
-    <xref linkend="step.update.check"/> for details).
+    <emphasis>cluster into maintenance mode</emphasis>, depending on if the
+    cluster stack is affected or not. See <xref linkend="step.update.check"/>
+    for details.
    </para>
    <para>
     If the cluster resource manager on a node is active during the software
@@ -661,10 +662,10 @@
      <listitem>
       <para>
        If none of the situations above apply, you do not need to stop the
-       cluster stack. In that case, put the cluster into maintenance mode
+       cluster stack. In that case, put the node into maintenance mode
        before starting the software update:
       </para>
-<screen>&prompt.root;<command>crm</command> configure property maintenance-mode=true</screen>
+<screen>&prompt.root;<command>crm</command> node maintenance <replaceable>NODE_NAME</replaceable></screen>
       <para>
        For more details on maintenance mode, see
        <xref linkend="sec.ha.config.basics.maint.mode"/>.
@@ -691,10 +692,10 @@
      </listitem>
      <listitem>
       <para>
-       or remove the cluster maintenance flag to bring the cluster back to
+       or remove the maintenance flag to bring the node back to
        normal mode:
       </para>
-<screen>&prompt.root;<command>crm</command> configure property maintenance-mode=false</screen>
+<screen>&prompt.root;<command>crm</command> node ready <replaceable>NODE_NAME</replaceable></screen>
      </listitem>
     </itemizedlist>
    </step>