docs(plugins): Fix grammar (#1998)

Author: newyork-anthonyng

src/content/api/plugins.md

@@ -71,7 +71,7 @@ compiler.hooks.run.tapPromise('MyPlugin', compiler => {
 ```
 
 The moral of the story is that there are a variety of ways to `hook` into the
-`compiler`, each allowing your plugin run as it sees fit.
+`compiler`, each one allowing your plugin to run as it sees fit.
 
 
 ## Custom Hooks

src/content/contribute/writing-a-plugin.md

@@ -12,7 +12,7 @@ Plugins expose the full potential of the webpack engine to third-party developer
 A plugin for `webpack` consists of
 
 - A named JavaScript function.
-- Defines `apply` method in it's prototype.
+- Defines `apply` method in its prototype.
 - Specifies an [event hook](/api/compiler-hooks/) on which to bind itself.
 - Manipulates webpack internal instance specific data.
 - Invokes webpack provided callback after functionality is complete.