Improve Translation Box

[remibetin]

• When the translation of WCAG guidelines and success criteria is not based on a WCAG Authorized Translation, we display a message in the translation box:

  This translation of WCAG 2 guidelines and success criteria is unofficial and might not accurately reflect the intentions of the English originals

  I suggest using the plural "English originals" since the wording comes from WCAG 2.0, 2.1 and 2.2.

  To add this message, add "wcagStatus": "unofficial" in src/locales/index.json (see Polish translation)

  Resolves Translations - Ack and disclaimer for unofficial translations #138

• Text in the translation box is now translatable (see French translation for example): just add and translate the following lines in src/locales/<lang>/UI/COMMON.json:

    "TRANSLATION_ABOUT": "About this translation",
    "TRANSLATION_DRAFT": "This volunteer translation is a <strong>draft</strong>. It contains English wording that will be translated soon.",
    "TRANSLATION_ACK": "See <a href='https://www.w3.org/WAI/eval/report-tool/acknowledgements'>Acknowledgements</a> for all translators and contributors.",
    "TRANSLATION_UNOFFICIAL": "This translation of WCAG 2 guidelines and success criteria is <strong>unofficial</strong> and might not accurately reflect the intentions of the <a href='https://www.w3.org/WAI/standards-guidelines/wcag/#versions'>English originals</a>."
  

  

[remibetin]

@iadawn @shawna-slh In this tool, the Polish translation of WCAG guidelines and criteria is not based on an Authorized Translation. When this is the case, this PR adds a disclaimer in the translation box. Ok for you?