Further cleanup of docs spelling

[freakboy3742]

The SSL error on macOS was caused because the PyPI name filter was turned on. This made every single one of the 440k names of PyPI packages a valid word in spelling. So... that needs to be turned off.

That removes the need for the SSL instructions in the contribution guide.

It also reveals a bunch of additional spelling problems. The only ones that aren't legitimate are the ones tied to a package name; for those, I've adopted the policy of:

• If it's being used in a "code" context, use the name as a literal
• If it's being used in a "text" context, ensure preferred project naming and capitalisation is used.

I've also updated all the links that were raising redirects. Ideally, redirects could be raised as an error, but that doesn't appear to be an option with Sphinx.

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct