Add procedure for corosync stage of crm cluster init

xml/ha_config_cli.xml

@@ -954,6 +954,87 @@ Membership information
    For more details, see
    <link xlink:href="https://crmsh.nongnu.org/crm.8.html#cmdhelp_corosync"/>.
   </para>
+
+  <para>
+    You can use the <command>crm cluster init</command>
+    script to change the &corosync; communication channels (or rings). For example, you might need
+    to switch from using two &corosync; rings to using a single ring with network device bonding,
+    or vice versa.
+  </para>
+  <procedure xml:id="pro-ha-config-crm-corosync">
+    <title>Changing &corosync; communication channels with &crmsh;</title>
+    <step>
+      <para>
+        Stop the cluster services on all nodes:
+      </para>
+<screen>&prompt.root;<command>crm cluster stop --all</command></screen>
+    </step>
+    <step>
+      <para>
+        On the first node, change &corosync;'s ring configuration with one of the
+        following commands:
+      </para>
+      <itemizedlist>
+        <listitem>
+          <para>
+            To configure one ring, run the script's <option>corosync</option> stage
+            with no additional parameters:
+          </para>
+<screen>&prompt.root;<command>crm cluster init corosync</command></screen>
+          <para>
+            Enter <literal>y</literal> to overwrite <filename>/etc/corosync/authkey</filename>
+            and <filename>/etc/corosync/corosync.conf</filename>, then accept the proposed
+            network address or enter a different one.
+          </para>
+        </listitem>
+        <listitem>
+          <para>
+            To configure two rings, specify two network addresses by using the
+            option <literal>--interface</literal> (or <literal>-i</literal>) twice:
+          </para>
+<screen>&prompt.root;<command>crm cluster init corosync -i eth0 -i eth1</command></screen>
+          <para>
+            Press <keycap>Enter</keycap> or enter <literal>y</literal> to accept all of the prompts.
+          </para>
+        </listitem>
+      </itemizedlist>
+    </step>
+    <step>
+      <para>
+        On <emphasis>only</emphasis> the first node, start the cluster services:
+      </para>
+<screen>&prompt.root;<command>crm cluster start</command></screen>
+    </step>
+    <step>
+      <para>
+        On each of the other cluster nodes, rejoin the cluster to update the
+        &corosync; configuration:
+      </para>
+      <itemizedlist>
+        <listitem>
+          <para>
+            For one ring, run the following command:
+          </para>
+<screen>&prompt.root;<command>crm cluster join -c <replaceable>NODE1</replaceable></command></screen>
+          <para>
+            Accept the proposed network address.
+          </para>
+        </listitem>
+        <listitem>
+          <para>
+            For two rings, specify the same network interfaces you used for the first node:
+          </para>
+<screen>&prompt.root;<command>crm cluster join -c <replaceable>NODE1</replaceable> -i eth0 -i eth1</command></screen>
+          <para>
+            Accept the proposed network addresses.
+          </para>
+        </listitem>
+      </itemizedlist>
+      <para>
+        This updates the &corosync; configuration and starts the cluster services on the node.
+      </para>
+    </step>
+  </procedure>
  </sect2>
 
  <sect2 xml:id="sec-ha-config-crm-setpwd">