3.10.0
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* Updates to Platform Overview (Federico Mena Quintero, Ekaterina Gerasimova)
* Updates to Platform Demos (Tiffany Ann Antopolski, Meg Ford, David King,
  Daniel Mustieles, Monica Kochofar)
* Updates to Accessibility Devel Guide (Andre Klapper)
* Updates to Optimization Guide (Lavanya, David King)
* Updated translations:
  cs      (Marek Černocký)
  de      (Christian Kirbach)
  el      (Dimitris Spingos)
  es      (Daniel Mustieles, Javier Ribera)
  gl      (Fran Diéguez)
  pt_BR   (Rafael Ferreira, Georges Neto, Georges Basile Stavracas Neto)