[amp-story-shopping] Add productDescription to all templates and max length

[processprocess]

productDescription is a required field.
This PR adds it to each example html template.

This PR also sets a max character length of 3000, and adds ellipses if it's over the limit.

[amp-owners-bot]

Hey @gmajoulet! These files were changed:

extensions/amp-story-shopping/0.1/amp-story-shopping-attachment.js
extensions/amp-story-shopping/0.1/test/test-amp-story-shopping-config.js

[mszylkowski]

I wonder (depending on how this is displayed) if you want to test different lengths of text for this section. It might be helpful to have larger LoremIpsums in there so we know how it looks. Still approving

[processprocess]

@jshamble Please be sure the validation for productDetails checks a minimum of 20 chars and max of 3,000 chars.

[jshamble]

@processprocess I am not sure if having a hard restriction would be beneficial given the discussion of other languages having different length requirements etc. See #37474 (comment)

[processprocess]

@processprocess I am not sure if having a hard restriction would be beneficial given the discussion of other languages having different length requirements etc. See #37474 (comment)

Got it! Thank you for the pointer to the discussion!