Improve json-ld output

[cmdoret]

The serialization of recipes to schema could be improved in several ways:

• The index of the step is encoded as free text in name, but HowToStep has a dedicated order integer property for it.
• Timers could be used to attach duration to HowToStep via timeRequired.
• Sections are ignored, maybe they could be included as headine or name, either on the first step of the section, or every step in the section?

I am happy to try and implement those, if that is something desirable!

Below is an example that illustrates those points.

---
title: Maple Chili Sweet Potatoes
cuisine: mediterranean
tags:
  - vegan
image: https://twocupsofhealth.com/wp-content/uploads/2019/11/BC0828DC-1C30-4246-AD43-D91793AE5C02.jpeg
---

== Preparation ==

Whisk @olive oil{2%tbsp}, @maple syrup{2%tbsp}, @chili powder{1%tsp}, @cayenne pepper{1/4%tsp}, 
and @salt{1/4%tsp} together.

== Cooking ==

Toss the glaze with @sweet potatoes{2%medium}(cut into 1.5 cm chunks) and spread on a #baking sheet{}. 
Roast at 220°C, stirring halfway through, until golden brown and tender, ~{40%minutes}.

{
  "@context": "https://schema.org",
  "@type": "Recipe",
  "image": "https://twocupsofhealth.com/wp-content/uploads/2019/11/BC0828DC-1C30-4246-AD43-D91793AE5C02.jpeg",
  "keywords": "vegan",
  "name": "Maple Chili Sweet Potatoes",
  "recipeCuisine": "mediterranean",
  "recipeIngredient": [
    "2 tbsp olive oil",
    "2 tbsp maple syrup",
    "1 tsp chili powder",
    "1/4 tsp cayenne pepper",
    "1/4 tsp salt",
    "2 medium sweet potatoes, cut into 1.5 cm chunks"
  ],
  "recipeInstructions": [
    {
      "@type": "HowToStep",
      "name": "Step 1",
      "text": "Whisk olive oil, maple syrup, chili powder, cayenne pepper, and salt together."
    },
    {
      "@type": "HowToStep",
      "name": "Step 2",
      "text": "Toss the glaze with sweet potatoes and spread on a baking sheet. Roast at 220°C, stirring halfway through, until golden brown and tender, 40 minutes."
    }
  ],
  "tool": [
    "baking sheet"
  ]
}