fixed some translation problems and updated some other sentences

1. Tag names like `video`、`track` do not have to be translated.
2. `Range` is a http request header, no need to be translated.
3. _Accessibility matters_ was translated into _辅助功能问题_, it's wrong, _matters_ here is a verb, doesn't mean _问题_(it means _problem_ in English).

One more question, is it all right to add me as a translator in such one?