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The yum command has been replaced by the dnf command in recent releases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

Also replace python-* packages by python3-* packages.

Change-Id: I0c4a420a78c848d8c139100bcc6ea83afefcf385

Author: kajinamit

doc/source/contributor/quickstart.rst

@@ -23,13 +23,8 @@ Install OS-specific prerequisites::
                      libmysqlclient-dev libxslt-dev libpq-dev git \
                      libffi-dev gettext build-essential python3-dev
 
-    # CentOS 7:
-    sudo yum install -y python-devel openssl-devel mariadb-devel curl \
-                        libxml2-devel libxslt-devel postgresql-devel git \
-                        libffi-devel gettext gcc
-
-    # Fedora/RHEL:
-    sudo yum install python-devel openssl-devel mysql-devel curl \
+    # Fedora/RHEL/CentOS:
+    sudo dnf install python3-devel openssl-devel mysql-devel curl \
                      libxml2-devel libxslt-devel postgresql-devel git \
                      libffi-devel gettext gcc
 

doc/source/install/install-guide-from-source.rst

@@ -27,15 +27,15 @@ Install and configure components
 
         .. code-block:: console
 
-           # yum install python-devel openssl-devel mariadb-devel \
+           # dnf install python-devel openssl-devel mariadb-devel \
                          libxml2-devel libxslt-devel postgresql-devel git \
                          libffi-devel gettext gcc
 
       * Fedora 21 / RHEL 7
 
         .. code-block:: console
 
-           # yum install python-devel openssl-devel mysql-devel \
+           # dnf install python-devel openssl-devel mysql-devel \
                          libxml2-devel libxslt-devel postgresql-devel git \
                          libffi-devel gettext gcc
 
@@ -224,7 +224,7 @@ Install the command-line client
 
      .. code-block:: console
 
-        # yum install python-devel openssl-devel python-virtualenv \
+        # dnf install python-devel openssl-devel python-virtualenv \
                       libffi-devel git gcc
 
    * Fedora 22 or higher

doc/source/install/install-rdo.rst

@@ -15,7 +15,7 @@ Install and configure components
 
    .. code-block:: console
 
-      # yum install openstack-magnum-api openstack-magnum-conductor python-magnumclient
+      # dnf install openstack-magnum-api openstack-magnum-conductor python-magnumclient
 
 .. include:: common/configure_2_edit_magnum_conf.rst
 

doc/source/user/index.rst

@@ -751,11 +751,11 @@ repositories for your distribution:
 
 Install using distribution packages for RHEL/CentOS/Fedora::
 
-    $ sudo yum install python-magnumclient
+    $ sudo dnf install python3-magnumclient
 
 Install using distribution packages for Ubuntu/Debian::
 
-    $ sudo apt-get install python-magnumclient
+    $ sudo apt-get install python3-magnumclient
 
 Install using distribution packages for openSUSE and SUSE Enterprise Linux::