Note GC and tail call support in Safari TP 202 (#397)

https://webkit.org/blog/15798/release-notes-for-safari-technology-preview-202/

features.json

@@ -209,15 +209,15 @@
 				"customAnnotationSyntaxInTheTextFormat": null,
 				"exceptions": "15.2",
 				"extendedConst": "17.4",
-				"gc": ["flag", "Requires JavaScriptCore flag `useWebAssemblyGC`"],
+				"gc": ["flag", "Supported in Safari Technology Preview 202"],
 				"multiValue": "13.1",
 				"mutableGlobals": "12",
 				"referenceTypes": "15",
 				"relaxedSimd": ["flag", "Requires JavaScriptCore flag `useWebAssemblyRelaxedSIMD`"],
 				"saturatedFloatToInt": "15",
 				"signExtensions": ["14.1", "Supported in desktop Safari since 14.1 and iOS Safari since 14.5"],
 				"simd": "16.4",
-				"tailCall": ["flag", "Requires JavaScriptCore flag `useWebAssemblyTailCalls`"],
+				"tailCall": ["flag", "Supported in Safari Technology Preview 202"],
 				"threads": ["14.1", "Supported in desktop Safari since 14.1 and iOS Safari since 14.5"],
 				"typedFunctionReferences": "18"
 			}