Fix decodedBodySize and encodedBodySize property names in resource-si…

…ze description (#2013)

Before:

> The decodedSize, encodedSize, and transferSize properties of the PerformanceResourceTiming API reports the size of resources loaded

After:

> The decodedBodySize, encodedBodySize, and transferSize properties of the PerformanceResourceTiming API reports the size of resources loaded

I know nothing about this feature, but this is what's documented at MDN.

features/resource-size.yml

@@ -1,5 +1,5 @@
 name: Resource size
-description: The `decodedSize`, `encodedSize`, and `transferSize` properties of the `PerformanceResourceTiming` API reports the size of resources loaded.
+description: The `decodedBodySize`, `encodedBodySize`, and `transferSize` properties of the `PerformanceResourceTiming` API reports the size of resources loaded.
 spec:
   - https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-decodedbodysize
   - https://w3c.github.io/resource-timing/#dom-performanceresourcetiming-encodedbodysize