Replace CentOS 7 references with EL8 (#441)

* Update QIG with EL8 and remove centos 7

* remove remaning mentions of centos 7

* Update _requirements.rst

* Update qig.rst

* Update qig.rst

* Update qig.rst

* Update qig.rst

* nmcli commands and corrections

* Update qig.rst

* Update qig.rst

---------

Co-authored-by: Andrija Panic <[email protected]>

Author: vishesh92

source/adminguide/templates/_cloud_init.rst

@@ -176,7 +176,7 @@ These features can be implemented in `“Linux Template creation process” <_cr
 
      ~ CentOS
 
-      Centos 7 root volume is /dev/centos/root if no changes are done during installation. Change the value accordingly if setup is different.
+      CentOS root volume is /dev/centos/root if no changes are done during installation. Change the value accordingly if setup is different.
 
       .. code:: bash
 	  

source/installguide/building_from_source.rst

@@ -483,9 +483,9 @@ Generating RPMs is done using the ``package.sh`` script:
 
 .. parsed-literal::
 
-   $ ./package.sh -d centos63
+   $ ./package.sh -d el8
 
-For other supported options(like centos7), run ``./package.sh --help``
+For other supported options, run ``./package.sh --help``
 
 That will run for a bit and then place the finished packages in
 ``dist/rpmbuild/RPMS/x86_64/``.

source/installguide/overview/_requirements.rst

@@ -29,7 +29,7 @@ Management Server may be placed on an Instance.
 
 -  Operating system:
 
-   -  Preferred: CentOS/RHEL 7.2+ or Ubuntu 16.04(.2) or higher
+   -  Preferred: EL8+ or Ubuntu 22.04 or higher
 
 -  64-bit x86 CPU (more cores results in better performance)
 

source/plugins/cloudian-connector.rst

@@ -229,8 +229,7 @@ settings. To enable the connector, ensure that the global setting
 "cloudian.connector.enabled" is set to true. Finally, restart each of the
 management server(s) to reload and enable the connector.
 
-For example, here is how you can restart the CloudStack management server
-installed on CentOS7:
+For example, here is how you can restart the CloudStack management server:
 
    ::