you must pdk bundle before bundle install

Summary
It is not enough to run bundle install inside a PDK generated module. You must run pdk bundle first.

Detail
On windows, I would like to be able to run bundle install against a PDK generated module so that I can run additional tools. This ticket is to tell anyone else attempting the same thing that to run pdk bundle to generate a magic Gemfile.lock before bundle install will work.

Steps to reproduce
1. Install ruby 2.4: {{choco install ruby --version 2.4.3.1 }} (must use 2.4 because PDK-1171)
2. Install pdk: choco install pdk
3. Generate a module pdk new module and follow the interview
4. bundle install

Now you receive a series of errors that can only be fixed by first running pdk bundle to generate a "fixed" Gemfile.lock. See narrative screenshots:

Desired improvement
Please could pdk bundle be more thoroughly documented, along with details of when/why it needs to be run and what else (if anything) it is doing