[ci-skip][doc] Fix typos and errors in wishlists.md

[hachi8833]

Motivation / Background

This Pull Request has been created because wishlists.md contains some errors and typos that disturbs running tests.

Detail

This Pull Request contains the following:

• Removing has_many :subscribers, dependent: :destroy from Product model because it includes Notifications concern that already declares the has_many: subscribers association. Current declaration is redundant and inconsistent with the final Product model in getting_started.md.
• Fixing incorrect filename app/models/wishlist.rb to app/models/wishlist_product.rb.
• Fixing incorrect path store_products_path to store_wishlists_path.
• Fixing incorrect call pluralize "Subscriber", @subscribers.count to pluralize @subscribers.count, "Subscriber".
• Fixing incorrect assertion "T-Shirt is already on Second Wishlist." to "T-Shirt is already on Second.".

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]

[skipkayhil]

Do the highlighted lines need to be updated?

[hachi8833]

I think so. In getting_started.md, the concern pp/models/product/notifications.rb already has the one:

module Product::Notifications extend ActiveSupport::Concern included do has_many :subscribers, dependent: :destroy # this should work after_update_commit :notify_subscribers, if: :back_in_stock? end

As far as I followed the steps in getting_started.md, the highlighted line has_many :subscribers, dependent: :destroy is unnecessary.

[skipkayhil]

I'm sorry, I should have been more specific: at the top of this code block is rb#5-6 which causes lines 5 through 6 to be highlighted in the generated guide. Since we're removing a line shouldn't we update which line numbers should be highlighted as well?

[hachi8833]

Aha, now I get this😅 Yes, I should have also updated the highlight from 5-6 to 4-5. Just a moment.