Switching documentation to be more clear about potential errors

Author: thedanvail

library/core/src/fmt/mod.rs

@@ -119,12 +119,9 @@ pub trait Write {
     ///
     /// This function will return an instance of [`Error`] on error.
     ///
-    /// Though it is possible for implementors of this trait to return an error, at the time
-    /// of writing these docs, no implementation of [`std::fmt::Write`] in the standard library
-    /// returns such an error.
-    ///
-    /// When working with external crates, it is advised to check the implementation of this
-    /// trait and anticipate any possible [`Error`]s.
+    /// The purpose of std::fmt::Error is to abort the formatting operation when the underlying
+    /// destination encounters some error preventing it from accepting more text; it should
+    /// generally be propagated rather than handled, at least when implementing formatting traits.
     ///
     /// # Examples
     ///