Clarify what documentation is being referenced

virsh.pod had several instances in which it referred to "the
documentation" which was a little puzzling to me since it is
documentation.  Reading the document from end to end makes it clear
that it means a specific URI which was noted previously in the text,
but I had never noticed those URIs in several years of referring to
the man page.  This patch adds those URIs to several additional places
in the text.

tools/virsh.pod

@@ -73,7 +73,7 @@ instead of the default connection.
 
 Enable debug messages at integer I<LEVEL> and above.  I<LEVEL> can
 range from 0 to 4 (default).  See the documentation of B<VIRSH_DEBUG>
-environment variable for the description of each I<LEVEL>.
+environment variable below for the description of each I<LEVEL>.
 
 =item B<-l>, B<--log> I<FILE>
 
@@ -249,7 +249,8 @@ connect to a local linux container
 
 =back
 
-For remote access see the documentation page on how to make URIs.
+For remote access see the documentation page at
+L<http://libvirt.org/uri.html> on how to make URIs.
 The I<--readonly> option allows for read-only connection
 
 =item B<uri>
@@ -1480,15 +1481,18 @@ format of the device sections to get the most accurate set of accepted values.
 
 =item B<attach-device> I<domain-id> I<FILE> [I<--config>]
 
-Attach a device to the domain, using a device definition in an XML file.
-See the documentation to learn about libvirt XML format for a device.
-If I<--config> is specified, alter persistent configuration, effect observed
-on next boot, for compatibility purposes, I<--persistent> is alias of
-I<--config>.
-For cdrom and floppy devices, this command only replaces the media within
-the single existing device; consider using B<update-device> for this usage.
-For passthrough host devices, see also B<nodedev-detach>, needed if
-the device does not use managed mode.
+Attach a device to the domain, using a device definition in an XML
+file using a device definition element such as <disk> or <interface>
+as the top-level element.  See the documentation at
+L<http://libvirt.org/formatdomain.html#elementsDevices> to learn about
+libvirt XML format for a device.  If I<--config> is specified the
+command alters the persistent domain configuration with the device
+attach taking effect the next time libvirt starts the domain.  For
+compatibility purposes, I<--persistent> is an alias of I<--config>.
+For cdrom and floppy devices, this command only replaces the media
+within an existing device; consider using B<update-device> for this
+usage.  For passthrough host devices, see also B<nodedev-detach>,
+needed if the device does not use managed mode.
 
 =item B<attach-disk> I<domain-id> I<source> I<target>
 [I<--driver driver>] [I<--subdriver subdriver>] [I<--cache cache>]
@@ -1571,14 +1575,15 @@ I<--config>.
 
 =item B<update-device> I<domain-id> I<file> [I<--config>] [I<--force>]
 
-Update the characteristics of a device associated with I<domain-id>, based on
-the device definition in an XML I<file>.
-If the I<--config> option is used, the changes will affect the next boot of
-the domain, for compatibility purposes, I<--persistent> is alias of
-I<--config>.
-The I<--force> option can be used to force device update, e.g., to eject a
-CD-ROM even if it is locked/mounted in the domain. See the documentation to
-learn about libvirt XML format for a device.
+Update the characteristics of a device associated with I<domain-id>,
+based on the device definition in an XML I<file>.  If the I<--config>
+option is used, the changes will take affect the next time libvirt
+starts the domain.  For compatibility purposes, I<--persistent> is
+alias of I<--config>.  The I<--force> option can be used to force
+device update, e.g., to eject a CD-ROM even if it is locked/mounted in
+the domain. See the documentation at
+L<http://libvirt.org/formatdomain.html#elementsDevices> to learn about
+libvirt XML format for a device.
 
 =item B<change-media> I<domain-id> I<path> [I<--eject>] [I<--insert>]
 [I<--update>] [I<source>] [I<--force>] [[I<--live>] [I<--config>] | [I<--current>]]
@@ -1710,8 +1715,9 @@ The I<--disable> option disable autostarting.
 
 =item B<net-create> I<file>
 
-Create a virtual network from an XML I<file>, see the documentation to get
-a description of the XML network format used by libvirt.
+Create a virtual network from an XML I<file>, see the documentation at
+L<http://libvirt.org/formatnetwork.html> to get a description of the
+XML network format used by libvirt.
 
 =item B<net-define> I<file>