rand_distr/std_math: add note regarding other dependents (#1421)

Author: dhardy

rand_distr/Cargo.toml

@@ -23,7 +23,12 @@ rustdoc-args = ["--generate-link-to-definition"]
 default = ["std"]
 std = ["alloc", "rand/std"]
 alloc = ["rand/alloc"]
+
+# Use std's floating-point arithmetic instead of libm.
+# Note that any other crate depending on `num-traits`'s `std`
+# feature (default-enabled) will have the same effect.
 std_math = ["num-traits/std"]
+
 serde1 = ["serde", "rand/serde1"]
 
 [dependencies]

rand_distr/README.md

@@ -25,7 +25,8 @@ The floating point functions from `num_traits` and `libm` are used to support
 `no_std` environments and ensure reproducibility. If the floating point
 functions from `std` are preferred, which may provide better accuracy and
 performance but may produce different random values, the `std_math` feature
-can be enabled.
+can be enabled. (Note that any other crate depending on `num-traits` with the
+`std` feature (default-enabled) will have the same effect.)
 
 ## Crate features