docs: add Jenkins CSP troubleshooting for blank static reports

[Hashim1999164]

Summary

• Adds a Troubleshooting section for blank static reports when viewed in Jenkins.
• Explains that Jenkins sandboxed iframes block scripts needed by the report.
• Points to the CSP workaround discussion in Add troubleshooting documentation for: Cannot display report in Jenkins due to sandboxed iframe #168.

Fixes #168

Test plan

• Confirm the new Troubleshooting subsection appears under the existing one in README.md
• Confirm the link to Add troubleshooting documentation for: Cannot display report in Jenkins due to sandboxed iframe #168#issuecomment-381748354 opens correctly

[linux-foundation-easycla]

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[changeset-bot]

⚠️ No Changeset found

Latest commit: 5996b70

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[alexander-akait]

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[valscion]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.29%. Comparing base (97d2ef8) to head (5996b70).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #724   +/-   ##
=======================================
  Coverage   76.29%   76.29%           
=======================================
  Files          17       17           
  Lines         983      983           
  Branches      357      357           
=======================================
  Hits          750      750           
  Misses        206      206           
  Partials       27       27           

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