Reference docker hub image for better user experience.

README.md

@@ -1,4 +1,10 @@
-# Run
+# Use with image from Docker Hub
 
-    docker build --tag ad .
-    docker run -v $PWD/path/to/asciidoc:/opt/docs -w /opt/docs ad "*.adoc"
+Convert all `.adoc` files in `path/to/asciidoc` into `.pdf` which will be placed in `path/to/asciidoc` as well.
+
+    docker run -v $PWD/path/to/asciidoc:/opt/docs -w /opt/docs hochzehn/asciidoctor-pdf "*.adoc"
+
+# Build locally
+
+    docker build --tag asciidoctor-pdf .
+    docker run -v $PWD/path/to/asciidoc:/opt/docs -w /opt/docs asciidoctor-pdf "*.adoc"