Linux: Remove outdated yum instructions (#1318)

Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>
Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>
Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: 4 people

getting-started/setup-building.rst

@@ -619,29 +619,25 @@ on Linux, macOS and iOS.
    distribution, but the appropriate commands for some popular distributions
    are below.
 
-   On **Fedora**, **Red Hat Enterprise Linux** and other ``yum`` based systems::
-
-      $ sudo yum install yum-utils
-      $ sudo yum-builddep python3
-
-   On **Fedora** and other ``DNF`` based systems::
+   On **Fedora**, **RHEL**, **CentOS** and other ``dnf``-based systems::
 
       $ sudo dnf install dnf-plugins-core  # install this to use 'dnf builddep'
       $ sudo dnf builddep python3
 
-   On **Debian**, **Ubuntu**, and other ``apt`` based systems, try to get the
+
+   On **Debian**, **Ubuntu**, and other ``apt``-based systems, try to get the
    dependencies for the Python you're working on by using the ``apt`` command.
 
    First, make sure you have enabled the source packages in the sources list.
    You can do this by adding the location of the source packages, including
    URL, distribution name and component name, to ``/etc/apt/sources.list``.
    Take Ubuntu 22.04 LTS (Jammy Jellyfish) for example::
 
-      deb-src http://archive.ubuntu.com/ubuntu/ jammy main
+      $ deb-src http://archive.ubuntu.com/ubuntu/ jammy main
 
    Alternatively, uncomment lines with ``deb-src`` using an editor, e.g.::
 
-      sudo nano /etc/apt/sources.list
+      $ sudo nano /etc/apt/sources.list
 
    For other distributions, like Debian, change the URL and names to correspond
    with the specific distribution.