Update usage instructions

[Morpheus636]

• Add instructions for installing zeal-cli with pip on Linux and Windows to the usage documentation.
• Add instructions for installing and using zeal-cli from binaries on Windows.
• Remove instructions for installing zeal-cli from source on Linux (no longer supported)

[kjaymiller]

To Complete This:

Add the following text to docs/usage.md

You can install this package using`pip install zeal-cli`