fix: markdownlint, hadolint (#527)

Author: lfrancke

template/.readme/partials/borrowed/documentation.md.j2.j2

@@ -1,9 +1,9 @@
 <!-- markdownlint-disable MD041 -->
 ## Documentation
 
-The stable documentation for this operator can be found [here](https://docs.stackable.tech/home/stable/{{operator_docs_slug}}).
+The stable documentation for this operator can be found in our [Stackable Data Platform documentation](https://docs.stackable.tech/home/stable/{{operator_docs_slug}}).
 If you are interested in the most recent state of this repository, check out the [nightly docs](https://docs.stackable.tech/home/nightly/{{operator_docs_slug}}) instead.
 
 The documentation for all Stackable products can be found at [docs.stackable.tech](https://docs.stackable.tech).
 
-If you have a question about the Stackable Data Platform contact us via our [homepage](https://stackable.tech/) or ask a public questions in our [Discussions forum](https://github.com/orgs/stackabletech/discussions).
+If you have a question about the Stackable Data Platform, contact us via our [homepage](https://stackable.tech/) or ask a public question in our [Discussions forum](https://github.com/orgs/stackabletech/discussions).

template/docker/Dockerfile.j2

@@ -82,8 +82,15 @@ assumeyes=True
 tsflags=nodocs
 EOF
 
+# SC2028
+# echo won't expand escape sequences. Consider printf.
+# https://github.com/koalaman/shellcheck/wiki/SC2028
+# Reason: This is complaining about the complicated PS1 statement.
+# It seems to work as intended so I'm not going to touch it!
+#
+# SC3037
 # It complains about echo flags not being available in POSIX sh but we set the shell to bash
-# hadolint ignore=SC3037
+# hadolint ignore=SC2028,SC3037
 RUN <<EOF
 # Update image and install kerberos client libraries as well as some other utilities
 microdnf update