fix(core): export useEnvelop plugin (#236)

Author: n1ru4l

.changeset/proud-pugs-search.md

@@ -0,0 +1,5 @@
+---
+'@envelop/core': patch
+---
+
+add missing useEnvelop plugin export

packages/core/src/index.ts

@@ -1,5 +1,6 @@
 export * from '@envelop/types';
 export * from './create';
+export * from './plugins/use-envelop';
 export * from './plugins/use-logger';
 export * from './plugins/use-timing';
 export * from './plugins/use-schema';