brief-yoctoprojectqs/index.rst: replace removed macro

The UBUNTU_DEBIAN_HOST_PACKAGES_ESSENTIAL macro was removed after
8d993022c2ae ("docs: use literalinclude for system requirements").
Replace by the literalinclude like in the reference manual.

Reported-by: "Robert P. J. Day" <rpjday@crashcourse.ca>
(From yocto-docs rev: 1316bd95f4c4107549de34b78bca0499233497e8)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/brief-yoctoprojectqs/index.rst

@@ -76,9 +76,10 @@ Build Host Packages
 
 You must install essential host packages on your build host. The
 following command installs the host packages based on an Ubuntu
-distribution::
+distribution:
 
-   $ sudo apt install &UBUNTU_DEBIAN_HOST_PACKAGES_ESSENTIAL;
+.. literalinclude:: ../tools/host_packages_scripts/ubuntu_essential.sh
+   :language: shell
 
 .. note::