[Docs] Change `withDockerfileFromBuilder` example to use expression Lamda (#975)
[Docs] Change `withDockerfileFromBuilder` example to use expression Lamda (#975)

Likely the preferable syntax. I've seen other examples in the user guide use this style e.g. under "Customizing the container".
outofcoffee/testcontainers-java,rnorth/test-containers,rnorth/test-containers,testcontainers/testcontainers-java,testcontainers/testcontainers-java,outofcoffee/testcontainers-java,outofcoffee/testcontainers-java,testcontainers/testcontainers-java,rnorth/test-containers