Update security policy and SLA

[gerald-hartig]

Link to issue number:

https://github.com/nvaccess/Internal-issue-tracking/issues/529

Summary of the issue:

Update security policy to clarify when security issues are submitted, for each severity level, what is our SLA, how many resources do we allocate, when do we release the patch & advisory?

Description of user facing changes

Documentation only: Security policy

Description of development approach

n/a

Testing strategy:

n/a

Known issues with pull request:

n/a

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes

[AppVeyorBot]

• PASS: Translation comments check.
• PASS: Unit tests.
• PASS: Lint check.
• FAIL: System tests (tags: installer NVDA). See test results for more information.
• Build (for testing PR): https://ci.appveyor.com/api/buildjobs/68pgh04522pua6rk/artifacts/output/nvda_snapshot_pr16303-31437,447c366b.exe
• CI timing (mins):
  INIT 0.0,
  INSTALL_START 1.0,
  INSTALL_END 0.9,
  BUILD_START 0.0,
  BUILD_END 29.2,
  TESTSETUP_START 0.0,
  TESTSETUP_END 0.4,
  TEST_START 0.0,
  TEST_END 2.3,
  FINISH_END 0.2

See test results for failed build of commit 447c366b72

[seanbudd]

Good work @gerald-hartig

[SaschaCowley]

Looks good!