fix some tag names (#26)

4.6.2-windowsservercore-ltsc2016/runtime/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/aspnet:4.6.2
+FROM microsoft/aspnet:4.6.2-windowsservercore-ltsc2016
 
 SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]
 

4.7-windowsservercore-ltsc2016/runtime/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/aspnet:4.7
+FROM microsoft/aspnet:4.7-windowsservercore-ltsc2016
 
 SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]
 

4.7.1-windowsservercore-ltsc2016/runtime/Dockerfile

@@ -1,4 +1,4 @@
-FROM microsoft/aspnet:4.7.1
+FROM microsoft/aspnet:4.7.1-windowsservercore-ltsc2016
 
 SHELL ["powershell", "-Command", "$ErrorActionPreference = 'Stop'; $ProgressPreference = 'SilentlyContinue';"]