External Branding: Check for spelling and casing

[tippexs]

In our docs, we are using brand names for reference. Some of them are outdated or incorrect.

Examples:

ARM is Arm.

This issue will be the base for a PR that will hold commits to fix these kind of issues.

[lcrilly]

There is more than one ARM architecture. Let's be specific.

[ac000]

Heh, I'm not stepping into that mine field! The most specific I'll go is Aarch64 (though we may work on some of older 32bit Arm stuff, I know Unit at least builds on 32bit x86...)