Document that PoolRealArray stores 32-bit floats

This closes #45230.

doc/classes/PoolRealArray.xml

@@ -4,8 +4,9 @@
 		A pooled [Array] of reals ([float]).
 	</brief_description>
 	<description>
-		An [Array] specifically designed to hold floating-point values ([float]). Optimized for memory usage, does not fragment the memory.
+		An [Array] specifically designed to hold floating-point values. Optimized for memory usage, does not fragment the memory.
 		[b]Note:[/b] This type is passed by value and not by reference.
+		[b]Note:[/b] Unlike primitive [float]s which are 64-bit, numbers stored in [PoolRealArray] are 32-bit floats. This means values stored in [PoolRealArray] have lower precision compared to primitive [float]s.
 	</description>
 	<tutorials>
 	</tutorials>