Tweak the language to be more clear about what not to do

Author: shana

README.md

@@ -4,7 +4,7 @@
 
 ### VS 2017 v15.3 users, please read
 
-The Visual Studio 2017 15.3 installer [has a bug](https://github.com/github/VisualStudio/issues/1206) that causes a corruption of the installed extensions data when you revert an installation of the extension (see also [this MS issue](https://developercommunity.visualstudio.com/content/problem/102178/error-installing-github-extension.html)). Until VS 2017 15.4 comes out, a workaround for this is explained in [#1206](https://github.com/github/VisualStudio/issues/1206)
+The Visual Studio 2017 15.3 installer [has a bug](https://github.com/github/VisualStudio/issues/1206) that causes a corruption of the installed extensions data when you revert an installation of the extension (see also [this MS issue](https://developercommunity.visualstudio.com/content/problem/102178/error-installing-github-extension.html)). Until VS 2017 15.4 comes out, avoid reverting the extension via `Extensions and Updates`. Steps for fixing the corrupted installation cache are in [#1206](https://github.com/github/VisualStudio/issues/1206)
 
 ### The location of the submodules has changed as of 31-01-2017