DEV 5.4 Use lang, abbr & acronym to embed useful information

Compare with WAI & NDA checkpoints
NDA checkpoints: 1.7 (P1) / 3.3 (P3)

Examples

Language change examples:

<html lang="en">
  ...
  <p>How do you say hello in French?</p>

  <p>You say
  <span lang="fr">Bonjour</span></p>
  <p>And in German?</p>
  <p lang="de">Guten tag </p>

  <p lang="ga">

  <a href="irishversion.html">
  as gaeilge </a></p>

Acronym examples:

...<acronym title="World Wide Web">

  WWW</acronym>...

... the <acronym title="National Disability Authority">NDA</acronym> is a...>