Reformulated remark for xmlns in root elements (TEI and teiCorpus)

[GusRiva]

This is to close issue #2621
Modifies the prose of the remark for TEI and teiCorpus. I slightly reformulated the suggestion from @sydb in the issue and added a Spanish translation as well.

[sydb]

Looks good to me, save two tiny typos. But I only looked at the English; leaving the Spanish review to @HelenaSabel.

[GusRiva]

Looks good to me, save two tiny typos. But I only looked at the English; leaving the Spanish review to @HelenaSabel.

Thanks! Corrected the typo in 4658cf1

[sydb]

Approving for the English portions. My Spanish is not good enough to qualify me to review the Spanish paragraph.

[HelenaSabel]

I suggested a few changes related to the Spanish translation of namespace (which, in my opinion should always be espacio de nombres)

[trishaoconnor]

This looks OK to merge to me, reviewer comments from @sydb and @HelenaSabel have been applied.