Add comment about potentially unsealing the trait

src/common.rs

@@ -6,8 +6,9 @@
 #![allow(missing_docs)]
 
 mod sealed {
-    /// A [sealed trait](https://predr.ag/blog/definitive-guide-to-sealed-traits-in-rust/) which stops this trait
-    /// from being derived outside the library.
+    /// A [sealed trait](https://predr.ag/blog/definitive-guide-to-sealed-traits-in-rust/)
+    /// which stops this trait from being derived outside the library. This could be relaxed
+    /// in the future if there is are good reasons to allow outside impls.
     pub trait FloatFuncsSealed {}
 }