Add the files for the jfahrer/envsubst image

[refs #d9ed9a0caa17]

Author: jfahrer

envsubst/Dockerfile

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+FROM debian:buster-slim
+
+RUN apt-get update && apt-get install gettext-base
+
+COPY example_file /
+
+CMD bash

envsubst/example_file

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+This is just some text to demonstrate envsubt.
+envsubst can substitute environment variables for you!
+
+It can replace VAR1 with the value of the env var: $VAR1
+And other vars as well: $OTHER