docs: extend documentation on Encode/Decode

sqlx-core/src/encode.rs

@@ -1,4 +1,5 @@
-//! Types and traits for encoding values to the database.
+//! Provides [`Encode`](trait.Encode.html) for encoding values for the database.
+
 use std::mem;
 
 use crate::database::{Database, HasArguments};
@@ -48,11 +49,6 @@ impl<'q, T, DB: Database> Encode<'q, DB> for &'_ T
 where
     T: Encode<'q, DB>,
 {
-    #[inline]
-    fn produces(&self) -> Option<DB::TypeInfo> {
-        (**self).produces()
-    }
-
     #[inline]
     fn encode(self, buf: &mut <DB as HasArguments<'q>>::ArgumentBuffer) -> IsNull {
         <T as Encode<DB>>::encode_by_ref(self, buf)
@@ -63,6 +59,11 @@ where
         <&T as Encode<DB>>::encode(self, buf)
     }
 
+    #[inline]
+    fn produces(&self) -> Option<DB::TypeInfo> {
+        (**self).produces()
+    }
+
     #[inline]
     fn size_hint(&self) -> usize {
         (**self).size_hint()