chore(fix): Fix some problems with demo quickref

[hughsw]

Marked version:

npm: 1.1.0

Markdown flavor: n/a

Description

• Fixes bugs and typos in demo/quickref.md

Expectation

Documentation will have correct English, all examples will work

Result

There are a couple of typos, and some of the examples don't work

What was attempted

I'm learning marked -- it's my first time looking at the docs

Contributor

• I'm new to this project; I don't know if/how your demos are tested...
• Test(s) exist to ensure functionality and minimize regression (if no tests added, list tests covering this PR); or,
• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

Committer

In most cases, this should be a different person than the contributor.

• Draft GitHub release notes have been updated.
• CI is green (no forced merge required).
• Merge PR

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[UziTech]

Thanks for this! There are a few things to fix.

[UziTech]

Suggested change

	and find that it's just wrapped in a `<p>` tag and *won't* be shown
	as preformatted text.
	and find that it's just wrapped in a `<p>` tag and *won't* be shown
	as preformatted text.

[UziTech]

Suggested change

	You can keep adding more and more paragraphs to a single
	list item by adding the traditional blank line and then keep
	on indenting the paragraphs with four spaces. You really need
	to only indent the first line, but that looks ugly.
	You can keep adding more and more paragraphs to a single
	list item by adding the traditional blank line and then keep
	on indenting the paragraphs with four spaces. You really need
	to only indent the first line, but that looks ugly.

[UziTech]

Suggested change

	You just need to indent eight spaces.
	You just need to indent six spaces.

[UziTech]

@hughsw are you interested in continuing with this PR?