Added info on MSStoreProductIdentifier to the 1.12.0 and 1.28.0 schema docs.

[Imre Eilertsen (DandelionSprout)]

📖 Description

I only learned about the feature at complete random while looking through the code of winget-cli, and goodness knows it's something I'd have wanted to know about for more than a year now.

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue (if applicable)
  • Based to some degree on Trying out the "msstore" installer type: Ubisoft.Connect version 172.1.0.13247 #416200.
  • Based to some degree on Added a note about MSStoreProductIdentifier non-support to RestInterface_1_1.cpp. winget-cli#6458.

📦 Manifest Checklist

• Checked that there aren't other open pull requests for the same manifest update/change
• This PR only modifies one (1) manifest
• Validated manifest locally with winget validate --manifest <path> (validation guide)
• Tested manifest locally with winget install --manifest <path>
• Manifest conforms to the 1.12 schema

Note: <path> is the directory containing the manifest you're submitting.

Microsoft Reviewers: Open in CodeFlow

[Imre Eilertsen (DandelionSprout)]

Closing in light of pl4nty/winget-extras#831 (comment).