add security bounty program

[danlipert]

Description

This PR adds new security bounty program guidelines to the docs site

Refers/Fixes

n/a

Testing

n/a

[codecov]

Codecov Report

Merging #5050 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5050   +/-   ##
=======================================
  Coverage   30.89%   30.89%           
=======================================
  Files         218      218           
  Lines       17476    17476           
  Branches     2394     2394           
=======================================
  Hits         5400     5400           
  Misses      11856    11856           
  Partials      220      220

---

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[codecov]

Codecov Report

Merging #5050 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #5050   +/-   ##
=======================================
  Coverage   30.89%   30.89%           
=======================================
  Files         218      218           
  Lines       17476    17476           
  Branches     2394     2394           
=======================================
  Hits         5400     5400           
  Misses      11856    11856           
  Partials      220      220

---

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 9c58a67...16ec6a0. Read the comment docs.