Added mermaid

Dockerfile

@@ -2,6 +2,7 @@ FROM rust:latest
 
 RUN git clone https://github.com/mdzk-rs/mdzk.git
 RUN cd mdzk && cargo build --release && cd /
+RUN cargo install mdbook-mermaid
 RUN cp ./mdzk/target/release/mdzk /bin
 
 WORKDIR /wiki

README.md

@@ -4,7 +4,7 @@ This is a *very* simple docker container for the
 [mdzk](https://github.com/mdzk-rs/mdzk) zettelkasten publishing framework.
 Created because reinstalling using docker for every automated build was too
 costly.  You can find it on
-[DockerHub](https://hub.docker.com/repository/docker/fr1nge/mdzk/).
+[DockerHub](https://hub.docker.com/r/fr1nge/mdzk/).
 To serve a zettelkasten on port 8080, the command is:
 
 ```