Fix docker instructions

[zba]

fixed:

docker-compose is very old depricated ,
misslead to update database from netbox container , why it shall not be postgres ?

improve:

easer way to deploy sql , just from stdin instead of trics with docker exec

[FlorianHeigl]

honestly that looks a lot more chaotic than the original one
sure - you can change the tires while driving - it's faster, saves on space etc. but it's also just more fragile and you'll not be able to tell what went wrong because it's just only got one failure more: FAIL CARCRASH.
the same, here you're putting two operations into one so some traceability is gone.

[zba]

honestly that looks a lot more chaotic than the original one sure - you can change the tires while driving - it's faster, saves on space etc. but it's also just more fragile and you'll not be able to tell what went wrong because it's just only got one failure more: FAIL CARCRASH. the same, here you're putting two operations into one so some traceability is gone.

Because it not uses docker ps command which makes things broken, it is just wrong way to do this this way (docker cp....) , also old instruction just outdated. not works, new one worked at moment of PR.
Also you not need to have netbox-demo repo pulled, just take sql.

In other words why you need to change tires, if it just traffic ligh stop ?