Add yamls to solution

Ix.NET/Source/Ix.NET.sln

@@ -7,6 +7,9 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Tests", "Tests", "{87534290
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{B733D97A-F1ED-4FC3-BF8E-9AC47A89DE96}"
 	ProjectSection(SolutionItems) = preProject
+		..\..\.vsts.ix-ci.yml = ..\..\.vsts.ix-ci.yml
+		..\..\.vsts.ix-pr.yml = ..\..\.vsts.ix-pr.yml
+		..\..\.vsts.ix-shared.yml = ..\..\.vsts.ix-shared.yml
 		CodeCoverage.runsettings = CodeCoverage.runsettings
 		Directory.build.props = Directory.build.props
 		Directory.build.targets = Directory.build.targets