Installation instructions need updating

[kinitawowi]

Since the move to Rush, the installation instructions are not helpful if you don't want to use heroku or docker.

The primary readme no longer has instruction ho to install from the github repo or other suitable sources like npm, or which would be preferable.
It's not clear if the instructions in the contributing guide are suitable for running a strider instance
The readme in the apps/strider folder is now incorrect
The instructions on https://strider-cd.github.io/guides/how-to-install.html are also incorrect.

[knownasilya]

Thanks for bringing this up. I've updated the guides, but have yet to deploy them. There is definitely more room for improvement and having one place for how to get started.

[knownasilya]

Should be published now, will keep this open for additional changes and cleanup.