review: clarify hex value

Author: inbelic

clang/test/CodeGenHLSL/RootSignature.hlsl

@@ -76,6 +76,7 @@ void RootDescriptorsEntry() {}
 // CHECK-SAME: i32 2, i32 3, i32 5,
 
 // checking mipLODBias, maxAnisotropy, comparisonFunc, borderColor
+// note: the hex value is the float bit representation of 12.45
 // CHECK-SAME: float 0x4028E66660000000, i32 9, i32 3, i32 2,
 
 // checking minLOD, maxLOD