move note on documentation quality into highlight box

source/contributing/how-to-contribute.md

@@ -27,14 +27,14 @@ Technical discussions happen in issue and pull request comments.
 If you are new to Nix, consider [contributing documentation](./documentation/index.md) first.
 
 This is where we need the most help and where it is the easiest to begin.
-:::
 
 Documentation and contribution guides are often incomplete or outdated, much as we would like them to be otherwise.
 We're working on it.
 You can help and improve the situation for everyone by immediately solving problems with the contribution workflow as you encounter them.
 This may slow you down with addressing your original concern.
 But it will make it a lot easier for anyone to make meaningful contributions in the future.
 And it will lead to better code and documentation in the long run.
+:::
 
 ## Report an issue