[DOM-49157] - Updated readmes

[ddl-olsonJD]

Link to JIRA

DOM-49157

What issue does this pull request solve?

Ambiguation in the number of apps that can exist per project

What is the solution?

Updated Apps description to state that only one is possible per project

Testing

Briefly describe how the change was tested. The purpose of this section is that a reviewer can identify a test gap, if any.

e.g. "I ran an upgrade from 4.2 to 4.6".

• Unit test(s)

Pull Request Reminders

• Has relevant documentation been updated?
• Does the code follow [Python Style Guide] (https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html)
• Update the changelog
• Are the existing unit tests still passing?
• Have new unit tests been added to cover any changes to the code?
• Has the JIRA ticket(s) been linked above?

References (optional)