feat: added keyword codec (partially works)

testdata/data/typo_section_header/input.md

@@ -0,0 +1,14 @@
+---
+@type: Recipe
+name: Typo Recipe
+---
+
+# Typo Recipe
+
+## Ingredints
+- Item 1
+- Item 2
+
+## Stps
+1. Step 1
+2. Step 2

testdata/data/typo_section_header/output.json

@@ -0,0 +1,13 @@
+{
+  "@context": "https://schema.org",
+  "@type": "Recipe",
+  "name": "Typo Recipe",
+  "recipeIngredient": [
+    "Item 1",
+    "Item 2"
+  ],
+  "recipeInstructions": [
+    "Step 1",
+    "Step 2"
+  ]
+}