[ci skip] Change the text color which wrapped by code tag.

[lanzhiheng]

Summary

As you can see, just use the fixed-width font will not be markedness about the code. I think we can use another color to make it clearer.

Other Information

[twitnithegirl]

I think this is a lot more readable.

[matthewd]

We're already using (a darker shade of) red to indicate links... using it for something non-clickable seems likely to confuse.

In our recent restyling of the API docs, we adopted a GitHub style background effect:

What do you think of adopting something closer to that? (Maybe even with a special yellowish variant in note blocks?)

[lanzhiheng]

@matthewd Thanks for your comments. I have changed the code, I use the #fff for code wrapped's background in the note, info, and todo section. And use #eee in normal text area. You can see the effect from the screenshot in PR. Is it OK now?