Update how-to for building Pro AMIs using Packer

Minor text changes plus replacing Ubuntu Advantage references

aws/aws-how-to/build-pro-ami-using-packer.rst

@@ -95,7 +95,7 @@ To add the source image, we can use Packer's image search functionality - ``sour
       "most_recent": true
    },
 
-If you are using the FIPS listings from AWS Marketplace, then use 679593333241 as the owner ID. Finally, complete the *builders* component by adding the username that'll be used to access the instance during provisioning:
+If you are using the FIPS listings from AWS Marketplace, then use 679593333241 as the owner ID (AWS' Marketplace ID). Finally, complete the *builders* component by adding the username that'll be used to access the instance during provisioning:
 
 .. code::
       
@@ -124,7 +124,7 @@ The first set used at the beginning includes a ``cloud-init status --wait`` comm
         ]
       },
 
-This wait command will tell the script to wait for the completion of all initialisation processes, including the Ubuntu Advantage activation. If you skip this command, you may face errors during the build process, since the Ubuntu Advantage client needs to change configurations and repositories right after booting up.
+This wait command will tell the script to wait for the completion of all initialisation processes, including the Ubuntu Pro activation. If you skip this command, you may face errors during the build process, since the Ubuntu Pro client needs to change configurations and repositories right after booting up.
 
 The second set of commands are included at the end and are used to perform clean-up:
 
@@ -140,15 +140,15 @@ The second set of commands are included at the end and are used to perform clean
       }
     ]
 
-These commands remove information that is specific to the instance being used to build the image, such as the machine ID and the token generated by Ubuntu Advantage. Doing this ensures that a generic AMI is created. So every time you spin up a new instance from this AMI, you'll have a “fresh start” with no duplication of unique information.
+These commands remove information that is specific to the instance being used to build the image, such as the machine ID and the token generated by Ubuntu Pro. Doing this ensures that a generic AMI is created, and each time you spin up a new instance from this AMI, you'll have a “fresh start” with no duplication of unique information.
 
 The rest of your personalised scripts or provisioning tools should go in between these two sets of commands. These two sets of commands can also be included directly within your script or provisioning tool.
 
 
 Build the AMI
 -------------
 
-The sample ``packer.json`` looks like:
+The complete sample ``packer.json`` looks like:
 
 .. code::
 
@@ -220,7 +220,7 @@ Log in to the instance and run:
 
    sudo ua status --wait
 
-The results should show that ``esm-apps``, ``esm-infra`` and ``livepatch`` are enabled, while entitlements exist for CIS, FIPS and CC-EAL.
+The results should show that the machine is attached to a Pro subscription and have ``esm-apps``, ``esm-infra`` and ``livepatch`` enabled.