add scope to named credential setup instructions

[subwayprophet]

Named Credential setup screenshot shows one Scope (which includes 'full' and works) but text instructions show another (which does not include 'full' and does not work -- returns INVALID_SESSION_ID). Added 'full' to Scope instructions in Named Credential setup text.

[salesforce-cla[bot]]

Thanks for the contribution! Before we can merge this, we need @subwayprophet to sign the Salesforce.com Contributor License Agreement.

[peterTrifecta]

Now that there is an Apex method for doing the search as of Summer '21, this should not be needed. The PLP search should be changed to use the Apex instead. Search products ConnectApi.CommerceSearch searchProducts(webstoreId, effectiveAccountId, productSearchInput)