Env Clarification

Clarified that the env variables here are an example output of env. The user should not set them to the example values.

Docker-DCO-1.1-Signed-off-by: Matthias Kühnle <git.nivoc@neverbox.com> (github: float64)
Fixed misspelling

Docker-DCO-1.1-Signed-off-by: Matthias Kühnle <git.nivoc@neverbox.com> (github: float64)
Reworded description of the environment variables

Removed the "test now..." b/c the code example is only about inspection
of env-variables.
Test follows in the next section.

Docker-DCO-1.1-Signed-off-by: Matthias Kühnle <git.nivoc@neverbox.com> (github: float64)
Updated environment description

.. to make it even more clear that this env variables are there because of the --link option.

Docker-DCO-1.1-Signed-off-by: Matthias Kühnle <git.nivoc@neverbox.com> (github: float64)
Reword - one sentence :-)

Docker-DCO-1.1-Signed-off-by: Matthias Kühnle <git.nivoc@neverbox.com> (github: float64)
Merge pull request #4147 from float64/patch-1

Env Clarification