Improve the content and flow of the backend readme

[SimiHunjan]

Problem

As I went to follow the the readme to set up the backend for the second time for local dev. I ran into issues again which I had to take @jbair06 precious time to help get it going. I took lots of notes and used it to rebuild the readme for the backend thinking from the perspective of how does a developer complete this in tasks and make it really easy as well as comprehensive like including screenshots where we can so its easy to reference what it being said in text.

Solution

Improve the readme such that a new developer can get going without getting stuck or the need to communicate with someone.

Alternatives

No response

[SimiHunjan]

As part of this update I will also be removing any areas in the .env files where we ask to . I discussed my suggestion with @jbair06 which was just to already have default values for these variables in the .env so the dev doesn't have to do anything. It gets confusing because you have to update them in multiple places and if they are not exactly the same then you have problems setting up up the backend.

Specific Example:

POSTGRES_DATABASE=<enter a database name>
POSTGRES_USERNAME=<enter a username>
POSTGRES_PASSWORD=<enter a password>

Just have something by default and the dev can change it if they want to but otherwise they are all set.

POSTGRES_DATABASE=postgres
POSTGRES_USERNAME=postgres
POSTGRES_PASSWORD=postgres

Related issue: #767

[SvetBorislavov]

I agree that the example.env should be prefilled with the default values, but we should not have "default" .env files.
We should leave the users to create them.

The reason for that is that when you have default .env files, this means it is not git ignored and when the user fulfills sensitive credentials there is a chance of committing the .env by mistake

[SvetBorislavov]

Fixed in #1351