Update the links to the Source Link spec (#2170)

This updates the links we had to the Source Link spec to point at the more official version.

CHANGELOG.md

@@ -7,7 +7,7 @@
 
 #### Debugger
 
-* Adds support for [Source Link](https://github.com/dotnet/core/blob/master/Documentation/diagnostics/source_link.md), Symbol Servers and other more advanced symbol options ([#373](https://github.com/OmniSharp/omnisharp-vscode/issues/373))
+* Adds support for [Source Link](https://aka.ms/SourceLinkSpec), Symbol Servers and other more advanced symbol options ([#373](https://github.com/OmniSharp/omnisharp-vscode/issues/373))
 * Adds launch.json option to suppress Just-In-Time compiler optimizations.
 * Due to the previous two items and work from the .NET Team, it is now possible to easily debug into ASP.NET itself in projects running against .NET Core 2.1 preview 1. Support for debugging into all the managed code in .NET Core will come in future .NET Core 2.1 builds. Instructions are in the [wiki](https://github.com/OmniSharp/omnisharp-vscode/wiki/Debugging-into-the-.NET-Framework-itself).
 

debugger-launchjson.md

@@ -183,7 +183,7 @@ The `symbolOptions` element allows customization of how the debugger searches fo
 
 ## Source Link options
 
-Source Link is a feature that makes it so that when you are debugging code that was built on another computer, such as code coming from a nuget package, the debugger can automatically bring up matching source code by downloading it from the web. To make this work, the .pdb files for the code you are debugging contains data that maps the source files in the DLL to a URL that the debugger can download from. More information about Source Link can be found at [https://github.com/dotnet/core/blob/master/Documentation/diagnostics/source_link.md](https://github.com/dotnet/core/blob/master/Documentation/diagnostics/source_link.md).
+Source Link is a feature that makes it so that when you are debugging code that was built on another computer, such as code coming from a nuget package, the debugger can automatically bring up matching source code by downloading it from the web. To make this work, the .pdb files for the code you are debugging contains data that maps the source files in the DLL to a URL that the debugger can download from. More information about Source Link can be found at [https://aka.ms/SourceLinkSpec](https://aka.ms/SourceLinkSpec).
 
 The `sourceLinkOptions` element in launch.json allows customization of Source Link behavior by URL. It is a map from URL to Source Link options for that URL. Wildcards are supported in the URL name. Currently the only customization is if Source Link is enabled for that URL, but more options may be added in the future.