Update Docker section formatting [skip ci]

* convert code block into Markdown for readability
* add link to the Dockerfile for easy reference

README.md

@@ -55,14 +55,12 @@ You can use the web version at [jsoncrack.com](https://jsoncrack.com) or also ru
 
 ## 🐳 Docker
 
-```
-A Docker file is provided in the root of the repository.
+A [`Dockerfile`](Dockerfile) is provided in the root of the repository.
 If you want to run JSON Crack locally:
 
-* Build Docker image with `docker build -t jsoncrack .`
+* Build a Docker image with `docker build -t jsoncrack .`
 * Run locally with `docker run -p 8888:8080 jsoncrack`
-* Go to [http://localhost:8888]
-```
+* Go to http://localhost:8888
 
 ## License