Document qa and qa-list shortcodes

[jdbaldry]

What

• add documentation for the qa shortcode
• add documentation for the qa-list shortcode
• include usage examples and produced output snippets

Part of https://github.com/grafana/website/pull/32564

[github-actions]

Readability report

File	AutomatedReadability	ColemanLiau	FleschKincaid	FleschReadingEase	GunningFog	LIX	SMOG
docs/sources/write/shortcodes/index.md	$${6.98\space\color{green}(Δ-0.02)}$$	$${10.56\space\color{red}(Δ+0.01)}$$	$${7.79\space\color{green}(Δ-0.01)}$$	$${56.48\space\color{red}(Δ-0.16)}$$	$${8.86\space\color{green}(Δ-0.01)}$$	$${38.97\space\color{red}(Δ+0.04)}$$	$${10.31\space\color{green}(Δ-0.03)}$$

View metric targets

Metric	Range	Ideal score
AutomatedReadability	6 (very easy read) to 14 (extremely difficult read)	8 or less
ColemanLiau	6 (very easy read) to 17 (extremely difficult read)	9 or less
FleschKincaid	6 (very easy read) to 17 (extremely difficult read)	8 or less
FleschReadingEase	100 (very easy read) to 0 (extremely difficult read)	70 or more
GunningFog	6 (very easy read) to 17 (extremely difficult read)	10 or less
LIX	20 (very easy read) to 60+ (extremely difficult read)	35 or less
SMOG	6 (very easy read) to 17 (extremely difficult read)	10 or less

[github-actions]

💻 Deploy preview available (Document qa and qa-list shortcodes):

• https://deploy-preview-writers-toolkit-1478-zb444pucvq-vp.a.run.app/docs/writers-toolkit/

[robbymilo]

Do we want this alphabetized?

[jdbaldry]

Do we want this alphabetized?

Good call out, done in fefc23a