Previously, names of CLI commands that also happened to be keywords were
shown in black color in the code block demonstrating the command's
usage. This worked fine when in light mode (where the code block
background is white) but not in the recently introduced dark mode (where
the code block background is dark gray).
This commit fixes this by ensuring the `.kwd` token color is inherited
from its parent (which has an appropriate color for the current theme).
Previously, the `.kwd` token was reset to its initial value (which is
`black` regardless of the theme).
**Before:** ![CLI pages keyword before][1]
**After:** ![cli-pages-keyword after][2]
[1]: https://user-images.githubusercontent.com/8604205/126073803-af317f0c-d04f-4c3a-9a83-e92541d7dd5a.png
[2]: https://user-images.githubusercontent.com/8604205/126073806-1d57e3ed-90b1-4735-ae2a-d0a39862bb95.png
PR Close#42889
e2aa7652e5
