WebAdministrationDsc: Move historic change log back to the file CHANGELOG.md

[johlju]

The reason we moved out the entries to a seperate files as mentioned below was fixed a long time ago, so we can now move the entries back.

WebAdministrationDsc/HISTORIC_CHANGELOG.md

Lines 3 to 6 in 1f5a356

	The release notes in the PowerShell Module manifest cannot exceed 10000
	characters. Due to a bug in the CI deploy pipeline this is not handled.
	This file is to temporary move the older change log history to keep the
	change log short.