SecurityPolicyDsc: Add Property Descriptions to the Schema MOF files and update README

[X-Guardian]

Pull Request (PR) description

This PR adds descriptions for all properties to the schema MOF files and updates the README file with the descriptions in a table layout.

This Pull Request (PR) fixes the following issues

None

Task list

• [x] Added an entry under the Unreleased section of the change log in the CHANGELOG.md. Entry should say what was changed, and how that affects users (if applicable).
• [x] Resource documentation added/updated in README.md.
• [x] Resource parameter descriptions added/updated in README.md, schema.mof and comment-based help.
• [ ] Comment-based help added/updated.
• [ ] Localization strings added/updated in all localization files as appropriate.
• [ ] Examples appropriately added/updated.
• [ ] Unit tests added/updated. See DSC Resource Testing Guidelines.
• [ ] Integration tests added/updated (where possible). See DSC Resource Testing Guidelines.
• [ ] New/changed code adheres to DSC Resource Style Guidelines and Best Practices.

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This change is 

[codecov-io]

Codecov Report

Merging #137 into dev will decrease coverage by 1%. The diff coverage is n/a.

@@        Coverage Diff         @@
##           dev   #137   +/-   ##
==================================
- Coverage   90%    89%   -2%     
==================================
  Files        5      5           
  Lines      573    498   -75     
==================================
- Hits       521    447   -74     
+ Misses      52     51    -1     

[X-Guardian]

Can someone review this PR? thanks.