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The yum command has been replaced by the dnf command in recent releases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: I0a1dfdaca91164eff2c25795f66976ec70356574

doc/source/guides/multinode-lab.rst

@@ -24,7 +24,7 @@ Install a couple of packages to bootstrap configuration:
 
 ::
 
-    apt-get install -y git sudo || yum install -y git sudo
+    apt-get install -y git sudo || dnf install -y git sudo
 
 Network Configuration
 ---------------------

doc/source/guides/single-machine.rst

@@ -62,7 +62,7 @@ to have sudo privileges:
 
 .. code-block:: console
 
-    $ apt-get install sudo -y || yum install -y sudo
+    $ apt-get install sudo -y || dnf install -y sudo
     $ echo "stack ALL=(ALL) NOPASSWD: ALL" | sudo tee /etc/sudoers.d/stack
 
 .. note:: On some systems you may need to use ``sudo visudo``.
@@ -81,7 +81,7 @@ We'll grab the latest version of DevStack via https:
 
 .. code-block:: console
 
-    $ sudo apt-get install git -y || sudo yum install -y git
+    $ sudo apt-get install git -y || sudo dnf install -y git
     $ git clone https://opendev.org/openstack/devstack
     $ cd devstack
 

doc/source/guides/single-vm.rst

@@ -56,8 +56,8 @@ passed as the user-data file when booting the VM.
     write_files:
       - content: |
             #!/bin/sh
-            DEBIAN_FRONTEND=noninteractive sudo apt-get -qqy update || sudo yum update -qy
-            DEBIAN_FRONTEND=noninteractive sudo apt-get install -qqy git || sudo yum install -qy git
+            DEBIAN_FRONTEND=noninteractive sudo apt-get -qqy update || sudo dnf update -qy
+            DEBIAN_FRONTEND=noninteractive sudo apt-get install -qqy git || sudo dnf install -qy git
             sudo chown stack:stack /home/stack
             cd /home/stack
             git clone https://opendev.org/openstack/devstack

doc/source/networking.rst

@@ -213,7 +213,7 @@ install ``sshuttle`` on your localhost:
 
 .. code-block:: bash
 
-    sudo apt-get install sshuttle || yum install sshuttle
+    sudo apt-get install sshuttle || dnf install sshuttle
 
 Finally, start ``sshuttle`` on your localhost using the floating IP address
 range. For example, assuming you are using the default value for

doc/source/plugins.rst

@@ -232,7 +232,7 @@ an early phase of its execution.  These packages may be defined in a
 plugin as files that contain new-line separated lists of packages
 required by the plugin
 
-Supported packaging systems include apt and yum across multiple
+Supported packaging systems include apt and dnf across multiple
 distributions.  To enable a plugin to hook into this and install
 package dependencies, packages may be listed at the following
 locations in the top-level of the plugin repository: