oatmeal-cookies.md: Reduce headings by one level

GitHub displays readmes in an HTML5 article tag so they should have
their own scope for heading levels.

oatmeal-cookies.md

@@ -1,9 +1,9 @@
-## Oatmeal cookies
+# Oatmeal cookies
 Originally from: http://www.epicurious.com/recipes/food/views/oatmeal-cookies-102276
 
 Makes: 24
 
-### Ingredients
+## Ingredients
 
 - 1 3/4 cups old-fashioned rolled oats
 - 3/4 cup all-purpose flour
@@ -16,7 +16,7 @@ Makes: 24
 - 1 large egg
 - 1/2 teaspoon vanilla
 
-### Method
+## Method
 Preheat oven to 375°F/190°C. Grease baking sheets.
 
 Stir together oats, flour, cinnamon, baking soda, and salt. Beat together butter, brown sugar, and granulated sugar in a large bowl with a fork or an electric mixer until light and fluffy. Add egg and vanilla and beat until combined well. Add oat mixture and beat until just combined.