SqlServerDsc: Update CHANGELOG with the historic changelog

[johlju]

Pull Request (PR) description

• Update CHANGELOG with the historic changelog

This Pull Request (PR) fixes the following issues

• Fixes SqlServerDsc: No longer a need for the historic changelog #1506

Task list

• Added an entry to the change log under the Unreleased section of the
  file CHANGELOG.md. Entry should say what was changed and how that
  affects users (if applicable), and reference the issue being resolved
  (if applicable).
• Resource documentation added/updated in README.md.
• 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 Community Testing Guidelines.
• Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[codecov]

Codecov Report

Merging #1525 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1525   +/-   ##
======================================
  Coverage      98%     98%           
======================================
  Files          39      39           
  Lines        5921    5921           
======================================
  Hits         5826    5826           
  Misses         95      95           

[johlju]

Reviewed 1 of 2 files at r1, 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved