Add Api.IntegrationTests to slnx

Author: Mpdreamz

docs-builder.slnx

@@ -77,6 +77,7 @@
   <Folder Name="/tests-integration/">
     <File Path="tests-integration/Directory.Build.props" />
     <Project Path="tests-integration/Elastic.Assembler.IntegrationTests/Elastic.Assembler.IntegrationTests.csproj" />
+	<Project Path="tests-integration/Elastic.Documentation.Api.IntegrationTests/Elastic.Documentation.Api.IntegrationTests.csproj" />
   </Folder>
   <Folder Name="/tests/">
     <File Path="tests/Directory.Build.props" />