Docs/clarify go dependency

[mbd-s]

This PR hopefully resolves any ambiguity about satisfying the Go dependency for this tool, as brought up in #134. It also makes some other small edits to the docs and command descriptions.

What does this do / why do we need it?

Installing m1-terraform-provider-helper via Homebrew also installs Go as a dependency, but it doesn't ensure that the Go installation is working. Since a working Go configuration is a requirement for using the tool, this PR clarifies the nature of the dependency and how to satisfy it.

How this PR fixes the problem?

By adding a sub-section (Installation > Dependencies) to the README.

What should your reviewer look out for in this PR?

How clear is the proposed wording? Does it fit with the existing style? Is a version bump supposed to be included as well?

Check lists

• Test passed
• Coding style (indentation, etc)

Additional Comments (if any)

Please consider the two docs commits entirely optional. Here's what I did:

• Replaced the Usage code block to show the actual current output
• Replaced references to M! with ARM, since this tool is also helpful for M2 and (probably soon) M3 Macs
• Fixed a few typos, standardized capitalization, and made a few other subjective style improvements

Which issue(s) does this PR fix?

fixes #134

[Junkern]

Thanks for the contribution! Will release a new patch version later today.