Add Security Audit Report on doc

[dongsam]

Description

Add security audit report of Least Authority on doc and link

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
write a little note why.

• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #429 (de3bf3a) into develop (5ffc15d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #429   +/-   ##
========================================
  Coverage    83.36%   83.36%           
========================================
  Files           20       20           
  Lines         2302     2302           
========================================
  Hits          1919     1919           
  Misses         218      218           
  Partials       165      165           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5ffc15d...de3bf3a. Read the comment docs.