Organize page Recipes better

[BurdetteLamar]

Makes it easier to understand what's here. Also, make level-1 headers more specific.

This is forward-looking. There will be more recipes, for example, about Parsing.

[kou]

Thanks!
(It may be better that we split the file instead of using deep nested sections.)

[BurdetteLamar]

I don't think it will be needed to nest deeper than this. But I do think it will be important for all recipes to be listed (and linked) in one place, so that readers can find the recipes they want.