feat: Add information on extra attributes on join table in N:M relati…

[garretaserra]

Added documentation for new functionality in sequelize/sequelize#16101

[ephys]

sequelize/sequelize#16101 targets the v7 branch but this documentation is written for v6

[garretaserra]

Moved documentation to v7

[ephys]

Thanks :)

Unfortunately your branch was outdated and the changes were made against the old version of the v7 docs, which were recently completely rewritten. Could you look into fixing the merge conflict?

I assume this could be documented as part of this section https://sequelize.org/docs/v7/associations/belongs-to-many/#association-setter-setx

[garretaserra]

I'm not sure where to put it exactly as it affects both the set and the add mixins.

[ephys]

That's a good point. I think it could go as a sub-section of this instead then: https://sequelize.org/docs/v7/associations/belongs-to-many/#customizing-the-junction-table

With mentions of set & add that links to the sections about set and add

About the content: While what you wrote still works in Sequelize 7, the new documentation uses the typescript + decorator approach first (with optional Tabs if we want to provide a typescript-free example)

[garretaserra]

It took a while because I had to learn how to correctly use the typescript definitions.

Also while working on the sscce for the documentation example I found I bug on the code for this update which I will be looking into.

Finally I think that its probably for the best to merge the documentation from Customizing the Junction Table nad what I did in the subsection Associations with extra attributes on through table by basing from the same example of person and toot.
What do you think?

On another note: The example of Person and Toot might not be the best. As a non native speaker I had barely heard the expression Toot, and a quick google search gives the following meaning:

toot
noun

1 a short, sharp sound made by a horn, trumpet, or similar instrument.
2 INFORMAL a snort of a drug, especially cocaine.
3 INFORMAL•NORTH AMERICAN a spell of drinking and lively enjoyment; a spree.

verb

1 sound (a horn or similar) with a short, sharp sound.
2 INFORMAL snort (cocaine).

[garretaserra]

Let me know if there is something more to do in this PR