docs: Edit fixes for IABv3 docs.

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<p>This documentation describes the fundamental In-app Billing components and 

features that you need to understand in order to implement your own In-app 

Billing application.</p>

features that you need to understand in order to add In-app 

Billing features into your application.</p>

<h2 id="api">In-app Billing API</h2>

<p>Your application accesses the In-app Billing service using an API that is 

complete, the application resumes.

</p>

<h2>The Sample Applications</h2>

<h2 id="samples">Sample Applications</h2>

<p>To help you integrate In-app Billing into your application, the Android SDK 

provides two sample applications that demonstrate how to sell in-app products 

from inside an app.</p>