chore: Fix missing curly brace (#337)

Author: nicjansma

index.html

@@ -941,7 +941,7 @@ <h3>
           {{PerformanceResourceTiming/transferSize}},
           {{PerformanceResourceTiming/encodedBodySize}}, and
           {{PerformanceResourceTiming/decodedBodySize}}. Further, the
-          {{PerformanceResourceTiming/nextHopProtocol} attribute will be set to
+          {{PerformanceResourceTiming/nextHopProtocol}} attribute will be set to
           the empty string.
         </p>
         <p>