Fix thread function of sync coroutines

[tapayne88]

Sorry if I've got this completely wrong!

I don't think the expected printed values of the sync coroutines function thread match up.

lua-async-await/README.md

Lines 118 to 123 in a54c078

	local thread = co.create(function ()
	local x = co.yield(1)
	print(x)
	local y, z = co.yield(2, 3)
	print(y)
	end)

lua-async-await/README.md

Line 128 in a54c078

We can expect to see `1`, `2 3` printed.

[tapayne88]

Found this too, pong expects a function to be passed and creates a thread itself

lua-async-await/README.md

Lines 217 to 224 in a54c078

	local thread = co.create(function ()
	local x, y, z = co.yield(echo(1, 2, 3))
	print(x, y, z)
	local k, f, c = co.yield(echo(4, 5, 6))
	print(k, f, c)
	end)
	pong(thread)