fix typo in migration-engine-plugins.md (#4842)

- trivial typo fix

docs/source/migration-engine-plugins.md

@@ -6,7 +6,7 @@ Apollo Server v2.18 deprecates the `engine` option to the `ApolloServer` constru
 
 Apollo Server ships with several plugins that help it integrate with Apollo Studio: the [usage reporting plugin](./api/plugin/usage-reporting/) plugin, the [schema reporting plugin](./api/plugin/schema-reporting/), and the [inline trace plugin](./api/plugin/inline-trace/). Apollo Server has some heuristics to install these plugins by default in certain circumstances (documented in the individual plugin reference pages), but otherwise they are standard [Apollo Server plugins](./integrations/plugins/). They are configured by passing arguments to the constructor functions. Some overall graph configuration (such as your graph API key and graph variant name) is set via the `apollo` option to the `ApolloServer` constructor (or via environment variables).
 
-Before Apollo Server v2.18, all this functionality built directly inside Apollo Server, and all of it was configured via the `engine` option to the `ApolloServer` constructor. While the `engine` option does continue to work for backwards compatibility, new configuration options will only be added to the plugins directly. To make it easier to undersatnd where configuration is coming from, you cannot mix and match the `engine` option with the three new plugins or the `apollo` option; if you want to start configuring the plugins directly you need to migrate all of your usage of the `engine` option to the plugin functions. Fortunately, this is relatively straightforward; most `engine` options correspond directly to an option passed to one of the plugins or on the `apollo` option to `ApolloServer`.  This page lists the options on `engine` and explains how to migrate them to the Studio integration plugins.
+Before Apollo Server v2.18, all this functionality built directly inside Apollo Server, and all of it was configured via the `engine` option to the `ApolloServer` constructor. While the `engine` option does continue to work for backwards compatibility, new configuration options will only be added to the plugins directly. To make it easier to understand where configuration is coming from, you cannot mix and match the `engine` option with the three new plugins or the `apollo` option; if you want to start configuring the plugins directly you need to migrate all of your usage of the `engine` option to the plugin functions. Fortunately, this is relatively straightforward; most `engine` options correspond directly to an option passed to one of the plugins or on the `apollo` option to `ApolloServer`.  This page lists the options on `engine` and explains how to migrate them to the Studio integration plugins.
 
 If you don't explicitly pass `engine` to your `ApolloServer` constructor, you don't need to make any changes! Specifically, configuration via the environment variables `APOLLO_KEY` (and its legacy equivalent `ENGINE_API_KEY`), `APOLLO_GRAPH_VARIANT` (and its legacy equivalent `ENGINE_SCHEMA_TAG`), and `APOLLO_SCHEMA_REPORTING` has not changed at all.