Add docs for hiding characters in a questions through an extension

[SebaMutuku]

IMPORTANT: Where possible all PRs must be linked to a Github issue

Fixes #3264

Engineer Checklist

• I have written Unit tests for any new feature(s) and edge cases for bug fixes
• I have added any strings visible on UI components to the strings.xml file
• I have updated the CHANGELOG.md file for any notable changes to the codebase
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the project's style guide
• I have built and run the FHIRCore app to verify my change fixes the issue and/or does not break the app
• I have checked that this PR does NOT introduce breaking changes that require an update to Content and/or Configs? If it does add a sample here or a link to exactly what changes need to be made to the content.

Code Reviewer Checklist

• I have verified Unit tests have been written for any new feature(s) and edge cases
• I have verified any strings visible on UI components are in the strings.xml file
• I have verifed the CHANGELOG.md file has any notable changes to the codebase
• I have verified the solution has been implemented in a configurable and generic way for reuseable components
• I have built and run the FHIRCore app to verify the change fixes the issue and/or does not break the app

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 29.4%. Comparing base (ac82739) to head (318d949).
Report is 53 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main   #3265     +/-   ##
=========================================
- Coverage     29.6%   29.4%   -0.2%     
- Complexity     658     693     +35     
=========================================
  Files          239     252     +13     
  Lines        11204   11911    +707     
  Branches      1948    2079    +131     
=========================================
+ Hits          3323    3512    +189     
- Misses        7447    7938    +491     
- Partials       434     461     +27     

Flag	Coverage Δ
engine	64.8% <ø> (-1.4%)	⬇️
geowidget	47.2% <ø> (ø)
quest	5.5% <ø> (+<0.1%)	⬆️

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see 10 files with indirect coverage changes