Convert to Jenkins Pipeline

Readme.md

@@ -1,4 +1,22 @@
-Docker Compose Example
+# PaperDockerBuilder
+
+Jenkins pipeline to build a Docker image of Paper.
+
+```bash
+Dockerfile  # used to build the Docker image
+Jenkinsfile # the pipeline file
+Readme.md   # you are reading this file
+run.sh      # entrypoint of the Docker image
+```
+
+## Pipeline process
+
+1. Fetches the information about the latest build of Paper for the provided MC version, from the [PaperMC API](https://api.papermc.io/v2/projects/paper)
+2. Downloads the Paper jar file.
+3. Builds the docker image with the downloaded jar and the entrypoint script, ensuring libraries are downloaded and Paper patch is applied.
+4. Pushes the image to the container registry with the tags `$mc_version` (e.g. `1.20.1`) and `$mc_version-$paper_build` (e.g. `1.20.1-196`)
+
+## Docker Compose Example
 
 ```yml
 version: "3"