apt over apt-get (#47663)

* apt over apt-get

* added note on apt-get for older versions

docs/docsite/rst/installation_guide/intro_installation.rst

@@ -145,12 +145,12 @@ To configure the PPA on your machine and install ansible run these commands:
 
 .. code-block:: bash
 
-    $ sudo apt-get update
-    $ sudo apt-get install software-properties-common
+    $ sudo apt update
+    $ sudo apt install software-properties-common
     $ sudo apt-add-repository --yes --update ppa:ansible/ansible
-    $ sudo apt-get install ansible
+    $ sudo apt install ansible
 
-.. note:: On older Ubuntu distributions, "software-properties-common" is called "python-software-properties".
+.. note:: On older Ubuntu distributions, "software-properties-common" is called "python-software-properties". You may want to use ``apt-get`` instead of ``apt`` in older versions.
 
 Debian/Ubuntu packages can also be built from the source checkout, run:
 
@@ -176,10 +176,10 @@ Then run these commands:
 .. code-block:: bash
 
     $ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 93C4A3FD7BB9C367
-    $ sudo apt-get update
-    $ sudo apt-get install ansible
+    $ sudo apt update
+    $ sudo apt install ansible
 
-.. note:: This method has been verified with the Trusty sources in Debian Jessie and Stretch but may not be supported in earlier versions.
+.. note:: This method has been verified with the Trusty sources in Debian Jessie and Stretch but may not be supported in earlier versions. You may want to use ``apt-get`` instead of ``apt`` in older versions.
 
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