Order support options alphabetically
Order support options alphabetically

Fixes https://github.com/prometheus/prometheus/issues/4080

Signed-off-by: Julius Volz <d7748b1e6f41fd74500c5ccae0980eab88c2ef61@gmail.com>

ddfreyne/prometheus-docs,ddfreyne/prometheus-docs,prometheus/docs,ddfreyne/prometheus-docs,prometheus/docs,prometheus/docs,ddfreyne/prometheus-docs