Update Regtest setup / define Regtest

[binaryflesh]

As a new user coming from the infosec side of things, 'Regtest' is usually thought as dynamic brute force analysis not the actual definition of regression testing. While writing an API binding for lbrycrd I was under impression using testnet was what I needed to use for unit tests to see if my code would work, not break. There is currently no highlight to point newbie devs to lbrycrd's useful feature and it would help others like myself

Tom edit:
This should also include an update of https://lbry.tech/resources/regtest-setup to include latest install instructions / orchestrate.

[tzarebczan]

hey @binaryflesh, thanks for opening the issue. I'll edit this to also include updating regtest instructions(may be out of date per my comment on the other issue).

[rhysmeister]

regtest setup instructions need an update...

https://lbry.tech/resources/regtest-setup

Several broken links to deleted repositories meaning getting a working env isn't possible.