Update src/OpenTelemetry.Exporter.OpenTelemetryProtocol/README.md

Co-authored-by: Utkarsh Umesan Pillai <66651184+utpilla@users.noreply.github.com>

src/OpenTelemetry.Exporter.OpenTelemetryProtocol/README.md

@@ -353,7 +353,7 @@ services.AddOpenTelemetry()
 > [!NOTE]
 > `DefaultRequestHeaders` can be used for [HTTP Basic Access
 Authentication](https://en.wikipedia.org/wiki/Basic_access_authentication). For
-more complex authentication requirement,
+more complex authentication requirements,
 [`System.Net.Http.DelegatingHandler`](https://learn.microsoft.com/dotnet/api/system.net.http.delegatinghandler)
 can be used to handle token refresh, as explained
 [here](https://stackoverflow.com/questions/56204350/how-to-refresh-a-token-using-ihttpclientfactory).