Add existing solution items

Author: YevgeniyShunevych

Atata.Configuration.Json.sln

@@ -7,9 +7,12 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Atata.Configuration.Json",
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{F6F0CC0A-EAE8-4D7F-8A87-F38178C7A84A}"
 	ProjectSection(SolutionItems) = preProject
+		.editorconfig = .editorconfig
 		azure-pipelines.release.yml = azure-pipelines.release.yml
 		azure-pipelines.runsettings = azure-pipelines.runsettings
 		azure-pipelines.yml = azure-pipelines.yml
+		Directory.Build.props = Directory.Build.props
+		Directory.Build.targets = Directory.Build.targets
 		README.md = README.md
 	EndProjectSection
 EndProject