doc: Use dnf instead of yum

The yum command has been replaced by the dnf command in recent releases
of Fedora-based distributions. Use the native command instead of
the alias kept for compatibility.

Change-Id: Ib002bdaf9058beb2fd2d2243948d3ec08bc0e588

doc/source/configuration/block-storage/drivers/dell-emc-powermax-driver.rst

@@ -1162,9 +1162,9 @@ On Red Hat Enterprise Linux and CentOS:
 
 .. code-block:: console
 
-   # yum install iscsi-initiator-utils   #ensure iSCSI is installed
-   # yum install device-mapper-multipath #multipath modules
-   # yum install sysfsutils sg3-utils    #file system utilities
+   # dnf install iscsi-initiator-utils   #ensure iSCSI is installed
+   # dnf install device-mapper-multipath #multipath modules
+   # dnf install sysfsutils sg3-utils    #file system utilities
 
 
 Multipath configuration file

doc/source/contributor/development.environment.rst

@@ -72,9 +72,9 @@ be added to the list above::
   python3-dev python3-pip
 
 On Red Hat-based distributions e.g., Fedora/RHEL/CentOS/Scientific Linux
-(tested on CentOS 6.5 and CentOS 7.3)::
+(tested on CentOS Stream 9)::
 
-  sudo yum install python-virtualenv openssl-devel python-pip git gcc libffi-devel libxslt-devel mysql-devel postgresql-devel
+  sudo dnf install python3-virtualenv openssl-devel python3-pip git gcc libffi-devel libxslt-devel mariadb-devel postgresql-devel
 
 On openSUSE-based distributions (SLES 12, openSUSE 13.1, Factory or
 Tumbleweed)::

doc/source/install/cinder-backup-install-rdo.rst

@@ -24,7 +24,7 @@ Install and configure components
 
    .. code-block:: console
 
-      # yum install openstack-cinder
+      # dnf install openstack-cinder
 
 
 #. Edit the ``/etc/cinder/cinder.conf`` file

doc/source/install/cinder-controller-install-rdo.rst

@@ -164,7 +164,7 @@ Install and configure components
 
    .. code-block:: console
 
-      # yum install openstack-cinder
+      # dnf install openstack-cinder
 
 #. Edit the ``/etc/cinder/cinder.conf`` file and complete the
    following actions:

doc/source/install/cinder-storage-install-rdo.rst

@@ -17,7 +17,7 @@ storage node, you must prepare the storage device.
 
      .. code-block:: console
 
-        # yum install lvm2 device-mapper-persistent-data
+        # dnf install lvm2 device-mapper-persistent-data
 
      .. end
 
@@ -119,7 +119,7 @@ Install and configure components
 
    .. code-block:: console
 
-      # yum install openstack-cinder targetcli
+      # dnf install openstack-cinder targetcli
 
    .. end