[llvm] LangRef: Clarify llvm.minnum and llvm.maxnum about sNaN and signed zero (PR #112852)

[YunQiang Su via llvm-commits]

================
@@ -16574,21 +16574,35 @@ type.
 
 Semantics:
 """"""""""
+Follows the IEEE-754 semantics for minNum, except that -0.0 < +0.0 for the purposes
+of this intrinsic. As for signaling NaNs, per the IEEE-754 semantics, if either operand
----------------
wzssyqa wrote:

The names of the operations are different in 2008 and 2019.
```   
2008 minNum
2019 minimumNumber
```

I don't think that it is a good idea to mention 2019 here, which will confuse the reader.
I will change IEEE-754 to IEEE754-2008 then to make it more clear.

https://github.com/llvm/llvm-project/pull/112852