Update README.md with usage and build instructions

README.md

@@ -2,5 +2,32 @@
 
 SimpleJarWrapper allows you to run another jar file as a subprocess.
 
+## Usage
+
+Download a release jar file from the [releases](https://github.com/ChargedByte/SimpleJarWrapper/releases) page or build
+it yourself.
+
+Place the jar file along with the configuration file in to a directory. You can see the example configuration
+file ***[here](wrapper.example.yaml)*** for the available options.
+
+Then you can just run the jar file with the following command:
+
+```shell
+$ java -jar SimpleJarWrapper-<VERSION>-all.jar
+```
+
+## Build
+
+Project is intended to be compiled with JDK 11 or later.
+
+Clone the repository to your desired location and run the following command to build the jar file:
+
+```shell
+$ ./gradlew build
+```
+
+This should produce a `SimpleJarWrapper-<VERSION>-all.jar` file in the `build/libs` directory.
+
 ## License
+
 This project is licensed under the [MIT license](LICENSE).