Add docs clarifying how to specify TLS configuration for docker images

[planetf1]

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We document how to configure TLS when running egeria at https://odpi.github.io/egeria-docs/guides/admin/configuring-the-omag-server-platform/?h=tls#brief-background-on-tls

However this only covers directly launching the chassis, and not when running in docker.

Our docker image for Egeria is based on Redhat UBI openjdk11 image. Various environment variables can be set.

We currently set ENV JAVA_OPTS_APPEND="-XX:MaxMetaspaceSize=1g"

to avoid some memory issues found with CTS, but more generally this environment variable allows other JVM options to be passed. This would include the ssl configuration referred to in the original link

The docs here should be extended to cover the docker image (there is currently none), and specifically how TLS can be configured when using the image

Further, this should be extended to our other docker images we build for connectors and UI (cc: @davidradl @sarbull @cmgrote @wbittles ) - some of these being based on other images

Also to note - as part of the work on the k8s operator, it too will be making TLS certs available via secrets, and in addition to documentation for the operator, it would be useful to document this technique for the benefit of those deploying with their own yaml/charts etc in k8s