Fix 1151-2: Added section & info surrounding re-authN for sensitive functionality / identity changes.

[alp1n3-eth]

This PR covers issue #1151.

• This PR handles the issue and requires no additional PRs.
• You have validated the need for this change.

What did this PR accomplish?

• It adds a section that explains the need for re-authN before any identity or sensitive functionality / config changes.
  • Requested changes are highlighted in this issue, along with deliverables: Need suggestion on issues mapping with wstg: Authenticator strength and Identity control issue #1151

Apologies for the delay on this. Hope you all had a nice holiday break!

[github-actions]

The following issues were identified:
document/4-Web_Application_Security_Testing/04-Authentication_Testing/09-Testing_for_Weak_Password_Change_or_Reset_Functionalities.md:168:596 MD009/no-trailing-spaces Trailing spaces [Expected: 0 or 2; Actual: 1]

[kingthorin]

The link check issue is a False Positive, it can be ignored.