Documentation:Update Documentation/zh_CN/arm64/booting.txt

This is a update of Chinese documentation: Documentation/zh_CN/arm64/booting.txt

It is based on the modifications of Documentation/arm64/booting.txt in submission:
"61bd93ce", "6c020ea8", "9d372c9f", "6d32ab2d".
And improve the format of documentation.

Signed-off-by: Fu Wei <wefu@redhat.com>
Reviewed-by: Weiwei Jia <harryxiyou@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>