docs: Fixed language directory issue.

<p>Android N brings more robust resource resolution, and

finds better fallbacks automatically. However, to speed up resolution and improve

 maintainability, you should store resources in the most common parent dialect.

 For example, if you were storing Spanish resources in the {@code es-US} directory

 before, move them into the {@code es-419} directory, which contains Latin American Spanish.

 Similarly, if you have resource strings in a folder named {@code en-GB}, rename

 the folder to {@code en-001} (international English), because the most common

 For example, if you were storing Spanish resources

 in the {@code values-es-rUS} directory

 before, move them into the {@code values-b+es+419} directory,

 which contains Latin American Spanish.

 Similarly, if you have resource strings in a

 directory named {@code values-en-rGB}, rename

 the directory to {@code values-b+en+001} (International

 English), because the most common

 parent for <code>en-GB</code> strings is {@code en-001}.

 The following examples explain why these practices improve performance and

reliability of resource resolution.</p>