Improve and update documentation: `TOC.md`

--

[✔] TOC.md
[ ] crossdomain.md
[ ] css.md
[ ] extend.md
[ ] faq.md
[ ] html.md
[ ] js.md
[ ] misc.md
[ ] usage.md
Improve and update documentation: `crossdomain.md`

* Remove `crossdomain.md` and move its update content into `misc.md`.

--

[✔] TOC.md
[✔] crossdomain.md
[ ] css.md
[ ] extend.md
[ ] faq.md
[ ] html.md
[ ] js.md
[ ] misc.md
[ ] usage.md
Improve and update documentation: `faq.md`

--

[✔] TOC.md
[✔] crossdomain.md
[ ] css.md
[ ] extend.md
[✔] faq.md
[ ] html.md
[ ] js.md
[ ] misc.md
[ ] usage.md
Improve and update documentation: `css.md`

--

[✔] TOC.md
[✔] crossdomain.md
[✔] css.md
[ ] extend.md
[✔] faq.md
[ ] html.md
[ ] js.md
[ ] misc.md
[ ] usage.md

Cc: @drublic