Update XenServer supported versions (#502)

Author: Pearl1594

source/installguide/hypervisor/xenserver.rst

@@ -36,12 +36,14 @@ System Requirements for XenServer Hosts
     -  XenServer 7.5
     -  XenServer 8.0 (not tested explicitly, but should work - see the release notes)
     -  XenServer 8.1 (not tested explicitly, but should work - see the release notes)
+    -  XenServer 8.4
     -  XCP-ng 7.4.0
     -  XCP-ng 7.5.0
     -  XCP-ng 7.6.0
     -  XCP-ng 8.0.0
     -  XCP-ng 8.1.0
     -  XCP-ng 8.2.0
+    -  XCP-ng 8.3.0
 
 
 -  You must re-install Citrix XenServer if you are going to re-use a

source/releasenotes/compat.rst

@@ -53,7 +53,9 @@ and VMware with vSphere.
 -  openSUSE Leap 15 with KVM
 -  SUSE Linux Enterprise Server 15 with KVM
 -  XCP-ng 8.2.0
+-  XCP-ng 8.3.0
 -  Citrix Hypervisor/XenServer version 8.2 (not tested, but expected to work. For 8.2 please check the note below) with latest hotfixes
+-  Citrix Hypervisor/XenServer version 8.4
 -  Debian 12 with KVM (not tested, but expected to work same as Ubuntu)
 
    .. note:: It is now required to enable HA on the XenServer pool in order to recover from a pool-master failure. Please refer to the `XenServer documentation <https://docs.citrix.com/en-us/xencenter/7-1/pools-ha-enable.html>`_.