Updated readme with instructions on verifying cross repo changes

README.md

@@ -31,5 +31,18 @@ any nupkg produced by the repo are copied into the local `.nuget` folder to be p
 repositories. The subfolders are built in dependency order.
 
 
+## Verifying cross repo changes
+You can use the Universe repo to preemptively verify and prepare follow ups for your breaking changes:
+- Clone the Universe repo https://github.com/aspnet/Universe 
+- Add a branch attribute to the build\Repositories.props file to point to your branch in the repo you’re trying to verify. For instance,
+  `<Repository Include="HtmlAbstractions" Commit="" />`
+  becomes
+  `<Repository Include="HtmlAbstractions" Commit="" Branch=”prkrishn/breaking-changes” />`
+- Run from the root of Universe, 
+  `build.cmd /p:CompileOnly=true /p:ShallowClone=true /p:BuildGraphOf=HtmlAbstractions`
+  This should clone and compile all the repos against your breaking changes branch. If you’d like to additionally run tests in all your dependencies (this will take a while), remove the first parameter: 
+  `build.cmd /p:ShallowClone=true /p:BuildGraphOf=HtmlAbstractions`
+  The ShallowClone property speeds up git clone and is optional in both cases.
+
 
 This project is part of ASP.NET Core. You can find samples, documentation and getting started instructions for ASP.NET Core at the [Home](https://github.com/aspnet/home) repo.