intro_installation: pass --include-injected in pipx upgrade example (#…

…745)

`--include-injected` ensures that the ansible-core package and other
packages that users may have injected into the ansible pipx venv are
updated alongside the ansible package.

docs/docsite/rst/installation_guide/intro_installation.rst

@@ -98,7 +98,7 @@ To upgrade an existing Ansible installation to the latest released version:
 
 .. code-block:: console
 
-    $ pipx upgrade ansible
+    $ pipx upgrade --include-injected ansible
 
 .. _pipx_inject: