Add FAQ entries for common syntax questions

[geoffromer]

No description provided.

[jonmeow]

I've given some suggestions for rephrasing. I think changing the phrasing a little may help people who are less familiar with Carbon.

[jonmeow]

Suggested change

	## Why is Carbon designed that way?
	## How were specific feature designs chosen?

Small suggestion: "that way" rings a bit disapproving to me, whereas this would be more something we could respond with:
"Throughout the design, we include 'Alternatives considered' and 'References' sections which can be used to research the decision process for a particular design." (like the second paragraph at https://github.com/carbon-language/carbon-lang/blob/trunk/docs/project/faq.md#what-can-i-do-if-i-disagree-with-a-design-decision)

[geoffromer]

Done.

[jonmeow]

Suggested change

	template parameters (or generic parameters), so if Carbon had angle brackets,
	[template parameters (and also generic parameters)](https://github.com/carbon-language/carbon-lang/blob/trunk/docs/design/README.md#checked-and-template-parameters), so if Carbon had angle brackets,

To my below comment, which I've marked resolved, I do think there should be some link/reference for what is used for template parameters. But maybe this reflects your intent?

(also, suggesting replacing "or" with "and also" to make clear to newcomers that "template" and "generic" aren't two terms for the same thing)

[geoffromer]

I've added the link, in a slightly different place.

(also, suggesting replacing "or" with "and also" to make clear to newcomers that "template" and "generic" aren't two terms for the same thing)

That feels awkward because we're inside a negation, and "not (A and B)" conveys less information than "not (A or B)". How about this instead?

[jonmeow]

LGTM, thanks!