Update fern/docs/pages/airdrop/initial-domain-mapping.mdx

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: tilenkavcic

fern/docs/pages/airdrop/initial-domain-mapping.mdx

@@ -119,7 +119,7 @@ Map one record type at a time, ensuring you map all required fields and as many
 
 For some required DevRev fields a fallback is required.
 
-The fallback you choose will be used on item creation if the extractor doesn't provide a value for the required DevRev field. 
+The fallback you choose is used on item creation if the extractor doesn't provide a value for the required DevRev field. 
 This is useful for fields that are required by DevRev but optional in the external system.
 
 ### Install the blueprint