docs: fix metafield and metaobject definition intent docs

[olavoasantos]

Description

Updates the documentation for Metafield Definition and Metaobject Definition intents to include the correct data parameters:

• Adds { ownerType: 'Product' } as the data parameter for Metafield Definition create and edit actions
• Replaces the value parameter with a data parameter { type: 'my_metaobject_definition_type' } for Metaobject Definition edit action
• Updates the corresponding example code for editing a Metaobject Definition to use the data parameter instead of the value parameter

🎩

• Verify that the updated documentation accurately reflects the expected parameters for these intents
• Confirm that the example code works correctly with the new parameter structure

Checklist

• I have 🎩'd these changes
• I have updated relevant documentation

[github-actions]

We detected some changes in packages/*/package.json or packages/*/src, and there are no updates in the .changeset directory. If the changes are user-facing and should cause a version bump, run yarn changeset to track your changes and include them in the next release CHANGELOG. If you are making simple updates to repo configuration, examples, or documentation, you do not need to add a changeset.