How to use a personal library in another project with Stack? (Haskell)

In Haskell, Haskell tool stack is quite difficult at least to me. For example, I want to use a personal library (a pre-release version of a Hackage package) from a stack project  in another stack project. Conceptually, it is simple, but it takes a bit long to find a solution from Stackoverflow.

• Link to the relevant article in Stackoverflow

Here is a summary.

In stack.yaml, 

packages 

- '.'

- path-to-a-stack-project-directory-containing-your-personal-library

In packages.yaml, 

dependencies:

- your-personal-libary

Then run 

$ stack build

This will solve your need. How easy it is after one knows how to do it! But I worry how difficult Haskell newbies may feel.