Fix a typo in make_rst.py (Packedfloat64Array -> PackedFloat64Array)

doc/tools/make_rst.py

@@ -150,7 +150,7 @@ PACKED_ARRAY_TYPES: List[str] = [
     "PackedByteArray",
     "PackedColorArray",
     "PackedFloat32Array",
-    "Packedfloat64Array",
+    "PackedFloat64Array",
     "PackedInt32Array",
     "PackedInt64Array",
     "PackedStringArray",