Tweak docs with warning to fix MithrilJS#2508 (MithrilJS#2895)

Co-authored-by: Barney Carroll <[email protected]>

docs/vnodes.md

@@ -112,11 +112,11 @@ When creating libraries that emit vnodes, you should use this module instead of
 
 ### Avoid anti-patterns
 
-#### Avoid memoizing mutable vnodes
+#### Avoid reusing vnodes
 
-Vnodes are supposed to represent the state of the DOM at a certain point in time. Mithril.js' rendering engine assumes a reused vnode is unchanged, so modifying a vnode that was used in a previous render will result in undefined behavior.
+Vnodes are supposed to represent the state of the DOM at a certain point in time. Mithril.js's rendering engine assumes a reused vnode is unchanged, so modifying a vnode that was used in a previous render will result in undefined behavior.
 
-It is possible to reuse vnodes to prevent a diff, but it's preferable to use the `onbeforeupdate` hook to make your intent clear to other developers (or your future self).
+It is possible to reuse vnodes in place to prevent a diff, but it's preferable to use the [`onbeforeupdate`](lifecycle.md#onbeforeupdate). 
 
 #### Avoid passing model data directly to components via attributes