Add initial README content

Author: nadeeshaan

README.md

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+# Language Server and Implementation
+This repository contains the source code for the example implementation of a language server referenced in the book \title of the book\.
+This language server implementation is associated with an example client implementation as well. The referenced client implementation is done for the [VS Code](https://code.visualstudio.com/) client.
+
+## About the Book
+### Authors
+- Nadeeshaan Gunasinghe - Technical Lead, WSO2 Inc (Pvt) Ltd.
+**Contact:**
+Email - nadeeshaangunasinghe@gmail.com
+LinkedIn - https://www.linkedin.com/in/nadeeshaan/
+Github: https://github.com/nadeeshaan
+
+- Nipuna Marcus - Technical Lead, WSO2 Inc (Pvt) Ltd
+**Contact:**
+Email - nipunamarcus2@gmail.com
+LinkedIn - linkedin.com/in/nipuna-marcus-0b721143
+Github: https://github.com/NipunaMarcus
+
+### Introduction
+
+## Technologies
+- The client implementation is done with [TypeScript](https://www.typescriptlang.org/).
+- Language Server implementation is done with Java and Java-11 would be preffered
+- Language Server implementation is done for the [Ballerina](https://ballerina.io/) programming language. The default implementation is done for [Ballerina Swan Lake Beta 3](https://ballerina.io/downloads/). You can read more and learn about Ballerina programming language in the [official doccumentation](https://ballerina.io/learn/)
+- [Gradle](https://gradle.org/) is used as the build tool for the server component
+- [Node JS](https://nodejs.org/en/) [v12.20.0 at least] and [NPM](https://www.npmjs.com/) [6.14.x at least] is used as for the client component
+
+## How to build
+This repository contains two components as the client and the server implementation. You have to build these components individually.
+
+##### Step 1
+Clone the repo
+
+##### Step 2
+**Build the Server Implementation**
+Go to the repo root and execute the following command to build the server implementation.
+`./gradlew clean build`
+The server implementation will copy the particular uber-jar artifact to `REPO_ROOT/client` directory.
+
+**Build the Client Implementation**
+Go to the `REPO_ROOT/client/ls-client` directory and execute the following command to install the Dependencies
+`npm install`
+Now execute the following command to build the client and generate the `.vsix` VS Code plugin artifact
+`npm run build`
+
+## Using the Extension and the Language Server
+### Prerequisites
+- Install [Ballerina SwanLake Beta3](https://ballerina.io/downloads/swan-lake-archived/)
+- Install [Java](https://www.oracle.com/java/technologies/downloads/)
+- Install [VS Code](https://code.visualstudio.com/Download)
+
+### Usage
+- Install the built `.vsix` extension artifact. The plugin itself will start the language server once a `.bal` file is opened
+- Open a Ballerina source file from the VSCode editor.
+- Explore the language features such as auto-completions, find references, and etc
+
+## Debugging the Implementation
+### Enable trace logs for the server implementation
+- You can explore the trace logs for the messages passed between the language server and the client by adding the following configuration option in the user settings.
+`"ballerina-lang-client.trace.server": "verbose"`
+
+### Debugging the Language Server
+##### Step 1
+Open the `REPO_ROOT/client/ls-client/` directory in VS Code.
+
+##### Step 2
+Go to `REPO_ROOT/client/ls-client/.vscode/launch.json` file and set the `LSDEBUG` config value to `true`
+
+##### Step 3
+Run the extension as shown in the figure