Update repo readme file.

[pbrubaker]

We need to update the repo README.md file to remove the text from the example and add more information, logo, Intel copyrights and such.

• Add docs for getting mono and installing it on linux and codespaces
• Add docs for building the extension
• List dependencies
• Update the extension readme, the repo location, and the changelog for the release.

[pbrubaker]

vscode-languageserver-csharp-example
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.

This text should also be updated. It should probably contain information from the readme that's in client-vscode/readme.md, plus anything that's required for contributors to build and run the development version.