Fixed "Public Docker image" link in README

Author: OrBin

README.md

@@ -99,7 +99,7 @@ Check out [OpenAPI-Spec](https://github.com/OAI/OpenAPI-Specification) for addit
     - [Docker](#docker)
       - [Development in Docker](#development-in-docker)
       - [Run docker in Vagrant](#run-docker-in-vagrant)
-      - [Public Docker image](#public-docker-image)
+      - [Public pre-built Docker images](#public-pre-built-docker-images)
     - [Homebrew](#homebrew)
   - [Getting Started](#getting-started)
   - Generators