[master] ef5aa1028 doc: Adapt build from source instructions for el9

[Dridi Boukelmoune]

commit ef5aa1028894d8198515f7bc2adee5adb6e86448
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Mon Jun 24 11:28:41 2024 +0200

    doc: Adapt build from source instructions for el9
    
    The libunwind and jemalloc packages appear to be gone, and the infamous
    PowerTools repository is also gone, but we find Sphinx in the new CRB
    repository instead. Probably because this landscape needed a little more
    complications.

diff --git a/doc/sphinx/installation/install_source.rst b/doc/sphinx/installation/install_source.rst
index 83c65c321..82bec51a9 100644
--- a/doc/sphinx/installation/install_source.rst
+++ b/doc/sphinx/installation/install_source.rst
@@ -90,29 +90,45 @@ in the following shell commands, replace ``sudo yum install`` if needed.
 
 Install sphinx
 
-* On Red Hat / CentOS 8, sphinx is not included in the default
-  repositories, so execute these steps to include it from the
-  powertools repository::
+* On Red Hat / CentOS 9, some packages are not included in the
+  default repositories, so execute these steps to include them
+  from the CRB repository::
 
     sudo dnf install -y 'dnf-command(config-manager)'
-    sudo yum config-manager --set-enabled powertools
-    sudo yum install -y diffutils python3-sphinx
+    sudo dnf config-manager --set-enabled crb
+    sudo dnf install -y \
+            diffutils \
+            python3-sphinx
 
-* On Red Hat / CentOS <= 7, install sphinx::
+* On Red Hat / CentOS 8, some packages are not included in the
+  default repositories, so execute these steps to include them
+  from the powertools repository::
 
-    sudo yum install -y python-sphinx
+    sudo dnf install -y 'dnf-command(config-manager)'
+    sudo dnf config-manager --set-enabled powertools
+    sudo dnf install -y \
+            diffutils \
+            jemalloc-devel \
+            libunwind-devel \
+            python3-sphinx
+
+* On Red Hat / CentOS <= 7, install the packages from the default
+  repository::
+
+    sudo yum install -y \
+            jemalloc-devel \
+            libunwind-devel \
+            python-sphinx
 
-The following step should conclude installation of the required
-packages::
+The following step should conclude installation of the remaining
+package dependencies::
 
   yum install -y \
 	make \
 	autoconf \
 	automake \
-	jemalloc-devel \
 	libedit-devel \
 	libtool \
-	libunwind-devel \
 	ncurses-devel \
 	pcre2-devel \
 	pkgconfig \