Desing principles - Support World Languages example added

In the design principles, at the Support World Languages item I have 
added the following paragraphs:

    *Example:* Text in element content has better language support than
    text in attribute content; in element content ruby annotations can
    be inserted, as well as dir attributes and bdo elements in case the
    Unicode bidirectional algorithm is insufficient to correctly order
    adjacent runs of mixed direction text.

    See W3C Internationalization (I18n) Activity
    <http://www.w3.org/International/>.


~Grauw

-- 
Ushiko-san! Kimi wa doushite, Ushiko-san nan da!!
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Laurens Holst, student, university of Utrecht, the Netherlands.
Website: www.grauw.nl. Backbase employee; www.backbase.com.