docs: networking: Fix failover build warnings

Currently building the net_failover docs causes a bunch of warnings to
be emitted.  These warnings are all related to indentation and correctly
highlight missing '::' (for code sections).  It looks, from other rst
files in Documentation, that the first column should be indented 2
spaces.

Add '::' before code snippets and indent all snippets uniformly starting
with 2 spaces.

Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/net_failover.rst

@@ -36,6 +36,7 @@ feature on the virtio-net interface and assign the same MAC address to both
 virtio-net and VF interfaces.
 
 Here is an example XML snippet that shows such configuration.
+::
 
   <interface type='network'>
     <mac address='52:54:00:00:12:53'/>
@@ -56,16 +57,17 @@ Here is an example XML snippet that shows such configuration.
 
 Booting a VM with the above configuration will result in the following 3
 netdevs created in the VM.
+::
 
-4: ens10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
+  4: ens10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
       link/ether 52:54:00:00:12:53 brd ff:ff:ff:ff:ff:ff
       inet 192.168.12.53/24 brd 192.168.12.255 scope global dynamic ens10
          valid_lft 42482sec preferred_lft 42482sec
       inet6 fe80::97d8:db2:8c10:b6d6/64 scope link
          valid_lft forever preferred_lft forever
-5: ens10nsby: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master ens10 state UP group default qlen 1000
+  5: ens10nsby: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master ens10 state UP group default qlen 1000
       link/ether 52:54:00:00:12:53 brd ff:ff:ff:ff:ff:ff
-7: ens11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master ens10 state UP group default qlen 1000
+  7: ens11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master ens10 state UP group default qlen 1000
       link/ether 52:54:00:00:12:53 brd ff:ff:ff:ff:ff:ff
 
 ens10 is the 'failover' master netdev, ens10nsby and ens11 are the slave
@@ -80,37 +82,38 @@ the paravirtual datapath when the VF is unplugged.
 
 Here is a sample script that shows the steps to initiate live migration on
 the source hypervisor.
+::
 
-# cat vf_xml
-<interface type='hostdev' managed='yes'>
+  # cat vf_xml
+  <interface type='hostdev' managed='yes'>
     <mac address='52:54:00:00:12:53'/>
     <source>
       <address type='pci' domain='0x0000' bus='0x42' slot='0x02' function='0x5'/>
     </source>
     <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
-</interface>
+  </interface>
 
-# Source Hypervisor
-#!/bin/bash
+  # Source Hypervisor
+  #!/bin/bash
 
-DOMAIN=fedora27-tap01
-PF=enp66s0f0
-VF_NUM=5
-TAP_IF=tap01
-VF_XML=
+  DOMAIN=fedora27-tap01
+  PF=enp66s0f0
+  VF_NUM=5
+  TAP_IF=tap01
+  VF_XML=
 
-MAC=52:54:00:00:12:53
-ZERO_MAC=00:00:00:00:00:00
+  MAC=52:54:00:00:12:53
+  ZERO_MAC=00:00:00:00:00:00
 
-virsh domif-setlink $DOMAIN $TAP_IF up
-bridge fdb del $MAC dev $PF master
-virsh detach-device $DOMAIN $VF_XML
-ip link set $PF vf $VF_NUM mac $ZERO_MAC
+  virsh domif-setlink $DOMAIN $TAP_IF up
+  bridge fdb del $MAC dev $PF master
+  virsh detach-device $DOMAIN $VF_XML
+  ip link set $PF vf $VF_NUM mac $ZERO_MAC
 
-virsh migrate --live $DOMAIN qemu+ssh://$REMOTE_HOST/system
+  virsh migrate --live $DOMAIN qemu+ssh://$REMOTE_HOST/system
 
-# Destination Hypervisor
-#!/bin/bash
+  # Destination Hypervisor
+  #!/bin/bash
 
-virsh attach-device $DOMAIN $VF_XML
-virsh domif-setlink $DOMAIN $TAP_IF down
+  virsh attach-device $DOMAIN $VF_XML
+  virsh domif-setlink $DOMAIN $TAP_IF down