465-Add contributing question

[lyashevska]

Description

• I have read the contribution guidelines
• This update is in line with what is recommended in the Python chapter of the Guide
• All user facing changes have been added to CHANGELOG.md

Related issues:

• Add optional question to copier questionnaire: contributing guidelines #465

Install the requirements

cd $(mktemp -d --tmpdir py-tmpl-XXXXXX)
pip install pipx
pipx install copier

Test 1:

Step-1:
Run the command below and say 'yes' to contributing guideline question.

copier copy --vcs-ref 465-contributing https://github.com/nlesc/python-template test_yes

Step-2:
Run the command below and say 'no'.

copier copy --vcs-ref 465-contributing https://github.com/nlesc/python-template test_no

What to check:
You should see the files below only when you say 'yes':

CONTRIBUTING.md
README.md should contain CONTRIBUTING section.
project_setup.md should contain CONTRIBUTING section.

[fdiblen]

Looks good! Please merge.