[DEFECT] Add Missing RWD Documentation.

[dylanjm]

Thank you for the defect report

• I am using the latest version of RAVEN.
• I have read the Wiki.
• I have created a minimum, reproducible example
  that demonstrates the defect.

Defect Description

PR #1640 was previously merged before proper documentation could be put in place. This issue was created to document this discrepancy in PR closure checklist.

Steps to Reproduce

No need to reproduce, it's missing.

Expected Behavior

Add documentation to tsa.tex in the doc.

Screenshots and Input Files

No response

OS

MacOS

OS Version

10.15.5

Dependency Manager

CONDA

For Change Control Board: Issue Review

• Is it tagged with a type: defect or task?
• Is it tagged with a priority: critical, normal or minor?
• If it will impact requirements or requirements tests, is it tagged with requirements?
• If it is a defect, can it cause wrong results for users? If so an email needs to be sent to the users.
• Is a rationale provided? (Such as explaining why the improvement is needed or why current code is wrong.)

For Change Control Board: Issue Closure

• If the issue is a defect, is the defect fixed?
• If the issue is a defect, is the defect tested for in the regression test system? (If not explain why not.)
• If the issue can impact users, has an email to the users group been written (the email should specify if the defect impacts stable or master)?
• If the issue is a defect, does it impact the latest release branch? If yes, is there any issue tagged with release (create if needed)?
• If the issue is being closed without a pull request, has an explanation of why it is being closed been provided?