The `ENV key value` form can be ambiguous, for example, the following defines
a single env-variable (`ONE`) with value `"TWO= THREE=world"`:
ENV ONE TWO= THREE=world
While we cannot deprecate/remove that syntax (as it would break existing
Dockerfiles), we should reduce exposure of the format in our examples.
Also updating some code-blocks that were missing language-hints
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Sebastiaan van Stijn