Move change log from README.md to CHANGELOG.md

[johlju]

We should move the change log out from the README.md and into a separate file CHANGELOG.md.

See example https://github.com/PowerShell/ActiveDirectoryDsc/blob/dev/CHANGELOG.md

Also in the README.md we should add a change log section. See example https://github.com/PowerShell/ActiveDirectoryDsc#change-log

[devevignesh]

I would like to claim this. Thanks

[johlju]

@devevignesh it's yours, looking forward to the PR! 😄

[johlju]

We must also update the first entry in the file https://github.com/PowerShell/xWebAdministration/blob/dev/.github/PULL_REQUEST_TEMPLATE.md. It should say that we should update the Unreleased section in CHANGELOG.md.

[devevignesh]

@johlju Opened PR for your review. Thanks.