[LangRef] Fix examples for float to int saturating intrinsics (llvm#115629)

As per the [LangRef:Simple
Constants](https://llvm.org/docs/LangRef.html#simple-constants), exact
decimal values of floating-point constants are required. For instance,
23.9 is a repeating decimal in binary and results in the reported error.

https://godbolt.org/z/1h7ETPnf6

Fixes llvm#113529.

Author: williamfedele

llvm/docs/LangRef.rst

@@ -20392,8 +20392,8 @@ Example:
 
 .. code-block:: text
 
-      %a = call i8 @llvm.fptoui.sat.i8.f32(float 123.9)              ; yields i8: 123
-      %b = call i8 @llvm.fptoui.sat.i8.f32(float -5.7)               ; yields i8:   0
+      %a = call i8 @llvm.fptoui.sat.i8.f32(float 123.875)            ; yields i8: 123
+      %b = call i8 @llvm.fptoui.sat.i8.f32(float -5.75)              ; yields i8:   0
       %c = call i8 @llvm.fptoui.sat.i8.f32(float 377.0)              ; yields i8: 255
       %d = call i8 @llvm.fptoui.sat.i8.f32(float 0xFFF8000000000000) ; yields i8:   0
 
@@ -20445,8 +20445,8 @@ Example:
 
 .. code-block:: text
 
-      %a = call i8 @llvm.fptosi.sat.i8.f32(float 23.9)               ; yields i8:   23
-      %b = call i8 @llvm.fptosi.sat.i8.f32(float -130.8)             ; yields i8: -128
+      %a = call i8 @llvm.fptosi.sat.i8.f32(float 23.875)             ; yields i8:   23
+      %b = call i8 @llvm.fptosi.sat.i8.f32(float -130.75)            ; yields i8: -128
       %c = call i8 @llvm.fptosi.sat.i8.f32(float 999.0)              ; yields i8:  127
       %d = call i8 @llvm.fptosi.sat.i8.f32(float 0xFFF8000000000000) ; yields i8:    0