messages.md: fix little typo

Author: tkrabel

packages/schema/messages.md

@@ -312,7 +312,7 @@ In protocol version `3.0.0` the kernel is considered the single source of truth
 
 In situations where a user does many changes to a widget on the frontend (e.g. moving a slider), the frontend will receive from the kernel many update messages (with the echo key set) from the kernel that can be considered old values. A frontend can choose to ignore all updates that are not originating from the last update it send to the kernel. This can be implemented by keeping track of the `msg_id` for each attribyte for which we send out an update message to the kernel, and ignoring all updates as a result from an `echo` for which the [`msg_id` of the parent header](https://jupyter-client.readthedocs.io/en/latest/messaging.html#parent-header) is not equal to `msg_id` we kept track of.
 
-For situations where sending back an echo update for a property is considered to expensive, we have implemented an opt-out mechanism in ipywidgets. A trait can have a `no_echo` metadata attribute to flag that the kernel should not send back an update to the frontends. We suggest other implementations implement a similar opt-out mechanism.
+For situations where sending back an echo update for a property is considered too expensive, we have implemented an opt-out mechanism in ipywidgets. A trait can have a `no_echo` metadata attribute to flag that the kernel should not send back an update to the frontends. We suggest other implementations implement a similar opt-out mechanism.
 
 #### State requests: `request_state`