dynamic animated text on landing page

[danbjoseph]

currently the landing page has static text

i think we should animate it like the text on https://rcrcsims.org so that it alternates between "digital" and "data management" (and then we can add more words in the future as other categories are added such as "health information" or "warehouse management" or whatever.)

and the subtext should be

With an array of tools and platforms to choose from, finding the right data management solution for your National Society's needs can be challenging.

(delete "data management" and capitalize "National Society")