Update README.md

Author: matarillo

README.md

@@ -1,2 +1,26 @@
 # vscode-languageserver-csharp-example
-Sample language server implemented in C#
+
+This repository contains a sample language server implemented in C#
+and a sample VS code extension that demonstrates an extension that runs the server.
+
+The extension observes all 'plaintext' documents (documents from all editors not associated with a language)
+and uses the server to provide validation and completion proposals.
+
+The code for the extension is in the 'client' folder. It uses the 'vscode-languageclient' node module to launch the language server.
+
+The language server is located in the 'server' folder. 
+
+# Modification from the original
+Sample language server is implemented in C#.
+
+# How to run locally
+* `cd server` to move the server folder.
+* `msbuild /t:Restore SampleServer.sln` to restore nuget packages.
+* `msbuild SampleServer.sln` to build the server.
+* `cd ../client` to move the client folder.
+* `npm install` to initialize the extension.
+* open `client` folder in VS Code.
+* 'Ctrl+Shift+B' to build the client and watch files.
+* In the Debug viewlet, run 'Launch Extension' from drop-down to launch the extension and attach to the extension.
+* create a file `test.txt`, and type `typescript`. You should see a validation error.
+* to debug the server use external debugger such as Visual Studio.