Issue #2486983 by metzlerd, jhodgdon, tim.plunkett: Document Text Input Form Elements

core/lib/Drupal/Core/Render/Element/Color.php

core/lib/Drupal/Core/Render/Element/Date.php

core/lib/Drupal/Core/Render/Element/Email.php

core/lib/Drupal/Core/Render/Element/File.php

core/lib/Drupal/Core/Render/Element/MachineName.php

core/lib/Drupal/Core/Render/Element/Number.php

core/lib/Drupal/Core/Render/Element/Password.php

core/lib/Drupal/Core/Render/Element/PasswordConfirm.php

core/lib/Drupal/Core/Render/Element/Range.php

core/lib/Drupal/Core/Render/Element/Search.php

core/lib/Drupal/Core/Render/Element/Tel.php

core/lib/Drupal/Core/Render/Element/Textarea.php

core/lib/Drupal/Core/Render/Element/Textfield.php

core/lib/Drupal/Core/Render/Element/Url.php

core/modules/filter/src/Element/TextFormat.php