This is exactly it: you can keep the snippets among your notes, so you can give a more detailed explanation, and they will be categorized due to the structure and of your notes (table of contents, links, etc.). If, on the other hand, you need the code snippet on the command line, you don't have to search through your notes, just search for the right keywords in Navi.
Its advantage over running snippets in a separate Navi file is that there is no duplication: if you realize that you need to add another parameter to a command in a snippet, you only need to edit it in your notes, you don't have to do it in the Navi file as well.