Including product attributes in site search - Concrete5 Community Store

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I have set up some products with the Concrete5 Community Store (https://github.com/concrete5-community-store/community_store) and given them a text attribute.
I'd like this text attribute to be searchable using the regular site search block.
I can see the table CommunityStoreProductSearchIndexAttributes is populated with the attributes text.

Can anyone tell me how to include this in the site search?

Many thanks

rosie607