docs: typo in training orientation

<p>Welcome to Android Training. Here you'll find a collection of classes that aim to help you

build great apps for Android, using best practices in a variety of framework topics.</p>

<p>Each class explains the steps required to solve a problem or implement a feature using plenty of

code snippets and sample code for you to use in your apps.</p>

<p>Each class explains the steps required to solve a problem or implement a feature using code

snippets and sample code for you to use in your apps.</p>

<p>This is just the beginning. We plan to add many more classes, expand and refine existing classes,

and build Training Courses that help you enhance your apps using an objective-oriented

collections of classes.</p>

<p>What you see now is just the beginning. We plan to add many more classes, expand and refine

existing classes, and build Training Courses that help you enhance your apps using

objective-oriented collections of classes.</p>