Very minor typo in directory name

[robertlipe]

I don't know how to create a PR for this.

In https://github.com/sakumisu/CherryUSB/tree/master/docs the first directory should probably be "assets" (resources belonging to a project" and not "asserts" (like a programmer checking that something is true).

Looks like a cool project! Congrats on creating it.

[sakumisu]

Thank you, this is a spelling error.

[sakumisu]

done