Suggest merging multiple env directives into one

[devunt]

As documentation describes, using merged form of ENV directives is preferred over the single form since it will yield smaller intermediate layers and containers.

Hence suggesting changing

ENV myName John Doe
ENV myDog Rex The Dog
ENV myCat fluffy

to

ENV myName="John Doe" \
    myDog="Rex The Dog" \
    myCat="fluffy"

seems reasonable.

[nexdrew]

Agreed, thanks for the suggestion!