Add "Related Recipes" section in individual recipe page

[FuqiX]

When I browse a recipe in the Cookbook website, I want to find all recipes related to the current recipe, so that I can be easily directed to other recipes and better decide which recipe to read first.

Example:
Recipe 1.3 is dependent on Recipe 1.2
Recipe 1.3 is related to Recipe 1.1 and [Recipe 3.1]

Possible solutions

1. Add a "related recipe" side panel in the recipe page. This might takes some work
2. Add a "related recipe" section in the recipe template. So that authors can link the recipes manually using hyperlinks.

One problem I had linking recipes manually is that some recipe links are not available yet.
Can we 'pre-register' the recipe, so that other recipes can point to the unfinished recipe? Or is it the editors' job to link the recipes manually?

[emilianoreynares]

This issue could be linked to the discussion about recipe coverage, tracking and overlaping (@nsjuty @proccaserra at 2020-06-03)

Development of a use case diagram (toy example here) could help?

[proccaserra]

now all recipes have a section "what to read next' with links to internal and external resources to the book.