docs: make 'python-moodle' the canonical command, 'py-moodle' the alias

[erseco]

Summary

Follows #83 (which added the python-moodle console-script alias). Now uses python-moodle as the canonical command everywhere in the docs and documents py-moodle as the shorter alias, so the command name matches the package name.

Changes

• All command examples across README.md and docs/** (courses/users/site/modules/sections/recipes/etc.) now use python-moodle ...; prose references to the tool use python-moodle.
• The alias is documented as the shorter equivalent py-moodle (installation & quickstart notes, README intro).
• pyproject.toml: list python-moodle first (canonical), py-moodle second (alias) — both still map to py_moodle.cli:app.
• Makefile: generate the CLI reference (docs/cli.md) with --name python-moodle, so the auto-generated help shows the canonical command.
• Preserved: the py-moodle-icon.png logo asset and the py_moodle import name. Also fixed a stray cd py-moodle and an inaccurate "project name is py-moodle" → python-moodle.

Verification

python -m typer py_moodle.cli.app utils docs --name python-moodle   # cli.md -> "python-moodle courses ..."
pyproject scripts == {python-moodle, py-moodle} -> py_moodle.cli:app
mkdocs build                                                        # clean; no stray "py-moodle <subcommand>" in rendered HTML
pytest tests/unit && flake8                                         # green

Backwards compatibility

Fully compatible — both commands still work; only the documented default changed. py-moodle remains a first-class alias.