Add link to core CStr stabilization announcement

serde/build.rs

@@ -116,6 +116,7 @@ fn main() {
     }
 
     // Support for core::ffi::CStr and alloc::ffi::CString stabilized in Rust 1.64.
+    // https://blog.rust-lang.org/2022/09/22/Rust-1.64.0.html#c-compatible-ffi-types-in-core-and-alloc
     if minor < 64 {
         println!("cargo:rustc-cfg=no_core_cstr");
     }