fix links to download pages for v1.1.5 (#1086)

Author: halex2005

release-notes/1.1/1.1.5.md

@@ -4,8 +4,8 @@
 
 ## Downloads
 
-* [.NET Core 1.0.8](https://github.com/dotnet/core/blob/master/release-notes/download-archives/1.0.8-download.md)
-* [.NET Core 1.1.5](https://github.com/dotnet/core/blob/master/release-notes/download-archives/1.1.5-download.md)
+* [.NET Core 1.0.8](https://github.com/dotnet/core/blob/master/release-notes/download-archives/1.0.8.md)
+* [.NET Core 1.1.5](https://github.com/dotnet/core/blob/master/release-notes/download-archives/1.1.5.md)
 
 After installing the .NET Core SDK 1.1.5, the following command will show that you're running version `1.1.5` of the tools.