Update SECURITY.md template and add it to Sampler repository

[johlju]

Pull Request

Pull Request (PR) description

Changed

• Update template for SECURITY.md and add it to Sampler repository as well.

Task list

• [x] The PR represents a single logical change. i.e. Cosmetic updates should go in different PRs.
• [x] Added an entry under the Unreleased section of in the CHANGELOG.md as per format.
• [ ] Local clean build passes without issue or fail tests (build.ps1 -ResolveDependency).
• [x] Documentation added/updated in README.md.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Unit tests added/updated. See DSC Community Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• [x] New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (5215bc7) 81% compared to head (d848246) 81%.

Additional details and impacted files

[](https://app.codecov.io/gh/gaelcolas/Sampler/pull/456?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Gael) ```diff @@ Coverage Diff @@ ## main #456 +/- ## =================================== Coverage 81% 81% =================================== Files 44 44 Lines 2328 2328 =================================== Hits 1904 1904 Misses 424 424 ```

[johlju]

Tested creating a module successfully using template dsccommunity and CompleteSample.