Preparing Release Notes: clarify stablizing trait impls

I've seen this done a few different ways (sometimes they even show up in the language section), and I think this is the way that makes the most sense.

Author: lolbinarycat

src/release/release-notes.md

@@ -48,6 +48,8 @@ Stabilized APIs and Const Stabilized APIs should both be formatted roughly as fo
 
 ```md
 - [`std::ptr::null_mut`](https://doc.rust-lang.org/std/ptr/fn.null_mut.html)
+<!-- for trait implemenations: -->
+- [`impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T>`](https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#impl-From%3C%26%5BT;+N%5D%3E-for-Vec%3CT,+Global%3E)
 ```
 
 Note that:
@@ -56,7 +58,10 @@ Note that:
 * the link is to stable docs (and so may not actually work at time of writing)
 * the API is directly noted. Sometimes we compress APIs (e.g., `uN` for
   unsigned integers) to avoid too much text.
-
+* link fragments can be long and hard to predict, so it is often better to copy and paste the url than write it manually
+  (if the item doesn't appear in stable docs, you can copy it from nightly and edit the url).
+* if the only thing being stablized is trait implementations (and not the corrosponding trait),
+  all impls are listed with links to the corrosponding impl blocks.
 ## Release team: Step 3: Confirm all issues/PRs needing relnotes are labeled `relnotes`
 
 This steps should happen in the first 3 weeks of the beta period (earlier is