Possible typo in warning message

[hallazzang]

Environment

• pip version: master branch, and checked for 19.3.1
• Python version: 3.8.0
• OS: alpine linux (actually, it's a docker image python:3.8-alpine)

Description
As you see below, the warning message is using terms --build-options, --global-options and --install-options but what pip actually accepts are --build-option, --global-option and --install-option(without s at the end).

pip/src/pip/_internal/cli/cmdoptions.py

Lines 85 to 88 in e3f9a72

	warnings.warn(
	'Disabling all use of wheels due to the use of --build-options '
	'/ --global-options / --install-options.', stacklevel=2,
	)

Expected behavior
The warning message should say --build-option, --global-option and --install-option to not confuse users.

How to Reproduce

1. Create a dummy requirements.txt with --install-option specified:

pip --install-option="-v"

2. Run this command:

$ python3 -m pip install -r requirements.txt

Output

/usr/lib/python3/dist-packages/pip/req/req_file.py:150: UserWarning: Disabling all use of wheels due to the use of --build-options / --global-options / --install-options.
  cmdoptions.check_install_build_global(options, opts)
Collecting pip (from -r requirements.txt (line 1))
  Using cached https://files.pythonhosted.org/packages/ce/ea/9b445176a65ae4ba22dce1d93e4b5fe182f953df71a145f557cffaffc1bf/pip-19.3.1.tar.gz
Skipping bdist_wheel for pip, due to binaries being disabled for it.
Installing collected packages: pip
  Running setup.py install for pip ... done
Successfully installed pip-19.3.1