docs: scripts: sphinx-pre-install: Fix building docs with pyyaml package

The Python module pyyaml is required to build the docs, but it is only
listed in Documentation/sphinx/requirements.txt and is therefore missing
when Sphinx is installed as a package and not via pip/pypi.

Add pyyaml as an optional package for multiple distros to fix building the
docs if you prefer to install Sphinx as a package.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Tested-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240208205550.984-1-thorsten.blum@toblux.com

scripts/sphinx-pre-install

@@ -361,6 +361,7 @@ sub give_debian_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
+		"yaml"			=> "python3-yaml",
 		"ensurepip"		=> "python3-venv",
 		"virtualenv"		=> "virtualenv",
 		"dot"			=> "graphviz",
@@ -395,6 +396,7 @@ sub give_redhat_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
+		"yaml"			=> "python3-pyyaml",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -477,6 +479,7 @@ sub give_opensuse_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
+		"yaml"			=> "python3-pyyaml",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -956,6 +959,7 @@ sub check_needs()
 
 	# Check for needed programs/tools
 	check_perl_module("Pod::Usage", 0);
+	check_python_module("yaml", 0);
 	check_program("make", 0);
 	check_program("gcc", 0);
 	check_program("dot", 1);