Instructions to import array module to test incomplete

[lucascolley]

array-api-tests/array_api_tests/__init__.py

Lines 13 to 14 in 606cc4d

	# You can comment the following out and instead import the specific array module
	# you want to test, e.g. `import array_api_strict as xp`.

array-api-tests/README.md

Line 39 in 606cc4d

Alternately, import/define the `xp` variable in `array_api_tests/__init__.py`.

They do not mention that you need to also define xp_name, since:

array-api-tests/conftest.py

Line 15 in 606cc4d

from array_api_tests import xp_name, xp as array_module