Grammar: Fix grammar for readability and clarity

Author: Trifall

docs/concept/plugin.md

@@ -33,12 +33,13 @@ const app = new Elysia()
     .listen(8080)
 ```
 
-Plugin can be registered by using `use` method.
+Plugins can be registered by using `use` method.
 
-Registering a plugin will combine types between plugin and current instance, and the scope of hooks and schema get merged as well.
+Registering a plugin will combine types between the plugin and current instance, and the scope of hooks and schema get merged as well.
 
 ## Separate file
-Using plugin pattern, you can define decouple your logic into a separate file.
+
+Using the plugin pattern, you can define and decouple your logic into a separate file.
 
 ```ts
 // plugin.ts
@@ -64,11 +65,11 @@ import { plugin } from './plugin'
 const app = new Elysia().use(plugin).listen(8080)
 ```
 
-Functional callback will allow user to access main instance values like routes schema, store.
+Functional callback will allow user to access main instance values like routes, schema, store, etc.
 
 ## Config
 
-You can customize plugin by creating function to return callback which accepts Elysia.
+You can customize a plugin by creating function to return callback which accepts Elysia.
 
 ```typescript
 import { Elysia } from 'elysia'