Update src/content/docs/bff/samples/index.mdx

Co-authored-by: Maarten Balliauw <maarten.balliauw@duendesoftware.com>

Author: RolandGuijt

src/content/docs/bff/samples/index.mdx

@@ -128,7 +128,7 @@ This sample shows how to host the BFF framework and IdentityServer with Docker.
 
 ## DPoP
 
-This sample shows how to configure the BFF for [DPoP](/identityserver/tokens/pop.md) so that is uses sender-constrained tokens.
+This sample shows how to configure the BFF for [DPoP](/identityserver/tokens/pop.md) so that it uses sender-constrained tokens.
 
 <LinkCard
   description="GitHub Repository for configuring DPoP with BFF"