Add help command to Makefile

[jonavellecuerdo]

Purpose and background context

It was decided that we include a 'help' command to the Makefile to give an overview of the available Makefile commands.

How can a reviewer manually see the effects of these changes?

Run make help. You should see the following:

(python-cli-template) jcuerdo@X4GPY162G1 python-cli-template % make help
Usage:  make <target>

Targets:
  help            preview Makefile commands
  install         install Python dependencies
  update          update Python dependencies
  test            run tests and print a coverage report
  coveralls       write coverage data to an LCOV report
  lint            run linters
  black           run 'black' linter and print a preview of suggested changes
  mypy            run 'mypy' linter
  ruff            run 'ruff' linter and print a preview of errors
  safety          check for security vulnerabilities and verify Pipfile.lock is up-to-date
  lint-apply      apply changes with 'black' and resolve 'fixable errors' with 'ruff'
  black-apply     apply changes with 'black'
  ruff-apply      resolve 'fixable errors' with 'ruff'

Includes new or updated dependencies?

NO

Changes expectations for external applications?

NO

What are the relevant tickets?

• https://mitlibraries.atlassian.net/browse/IN-894

Developer

• All new ENV is documented in README
• All new ENV has been added to staging and production environments
• All related Jira tickets are linked in commit message(s)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer(s)

• The commit message is clear and follows our guidelines (not just this PR message)
• There are appropriate tests covering any new functionality
• The provided documentation is sufficient for understanding any new functionality introduced
• Any manual tests have been performed and verified
• New dependencies are appropriate or there were no changes

[ghukill]

Left a comment about double ampersands, but that's either true / not true, and approved either way! Looks good, thanks for this.