RK3568 fixes.

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This PR includes 3 commits:

• Change RK3568 10.1 inch images, two grey two black, please see if we need more images to be listed.
• Fix some typos. Will refactor the 5inch and 7inch docs to share the same include files later.
• Remove two labels, these power-table labels are not referenced in any of the documents, but Sphinx complains they're duplicated labels. There are other warnings from Sphinx on other pages of this docs as well, such as the AM335X, RK3399 and Pi docs, on duplicate labels. Will try to remove them later.

Infected pages:

The RK3568 hardware index page and its 5, 7, 10.1 inch product pages.