Fix documentation for clearCustomerCart

[danmooney2]

Update documentation to match definitions in the schema files.

Purpose of this pull request

This pull request (PR) fixes descriptions of input/output for clearCustomerCart.

Affected DevDocs pages

• https://devdocs.magento.com/guides/v2.4/graphql/mutations/clear-customer-cart.html

Links to Magento source code

• https://github.com/magento-commerce/magento2b2b/blob/caae8db28cc56efce89fbc707d06b195285ff814/app/code/Magento/RequisitionListGraphQl/etc/schema.graphqls#L185
• https://github.com/magento-commerce/magento2b2b/blob/caae8db28cc56efce89fbc707d06b195285ff814/app/code/Magento/RequisitionListGraphQl/etc/schema.graphqls#L98

[keharper]

@danmooney2 Can this be merged now, or does it need to wait to the next release of B2B?

[danmooney2]

Hi @keharper, this change is a fix for an issue in existing releases and does not need to wait to be merged.

[keharper]

@magento import code to magento-devdocs/devdocs

[m2-github-services]

@keharper the branch with the code is successfully imported into the magento-devdocs/devdocs repository. Branch name: imported-danmooney2-devdocs-9531.