Update ui.md

Fixed grammar.

IdentityServer/v6/docs/content/samples/ui.md

@@ -9,7 +9,7 @@ These samples illustrate customization of the [interactive pages]({{< ref "/ui"
 ### Custom Profile Service
 This sample shows how to create a [custom profile service]({{<ref "/fundamentals/claims">}}) to control what claims are issued from your IdentityServer. The majority of the sample is captured in *CustomProfileService.cs* in the *IdentityServer* project.
 
-Also, another part of the sample shows how to collect a custom claim during the login workflow when using an external login provider (this is done in the *ExternalLogin/Callback.cshtml.cs* processing logic). This claim value then is stored the user's session, and then ultimately is copied into the created tokens via the custom profile service logic.
+Also, another part of the sample shows how to collect a custom claim during the login workflow when using an external login provider (this is done in the *ExternalLogin/Callback.cshtml.cs* processing logic). This claim value is then stored in the user's session, and is then ultimately copied into the created tokens via the custom profile service logic.
 
 [link to source code]({{< param samples_base >}}/UserInteraction/ProfileService)