Slightly change dockerisation approach and add better docs/directions

[benjiboi214]

Hi!

Thanks for everyone's hard work here so far, love having a place to start.

I've just been through a bit of an effort trying to get this repo running in my k8s environment and ran into a few gotchas that no doubt will cause others some pain in the future.

Notably:

• Injecting secrets into the config run.sh (setup_keys/create_settings) after build is a nightmare and leads to issues down the road if you try to add caching
• Running the tendenci start project in the install.sh script means that when using k8s you have issues where the volume I want to mount to persist the project settings overwrites the container's existing project content.
• No support for the prod install settings (libmemcached)
• No support for things like CONN_MAX_AGE or SSL mode on DB connections (much needed for the number of DB requests tendenci seems to make)

I have a branch in my fork that needs a bit of a clean up, but wondering if you would be interested in looking at a PR at some point in the near future? If yes, can actually do the clean up and make it worthy of a merge :D

Thanks in advance.

[jennyq]

@benjiboi214,
Yes, PRs are always welcome. Thank you!