Fixes #104 (#107)
Fixes #104 (#107)

Fix "Hello world explainer" broken image link by replacing "png" with "svg"
ManoMarks/play-with-docker.github.io,play-with-docker/play-with-docker.github.io,play-with-docker/play-with-docker.github.io,ManoMarks/play-with-docker.github.io