Add version 1.0 of the AES-128 example.

- Add the initial version of both the VHDL and the SystemVerilog version of the AES-128 example, which accompanies the book by Hubert Kaeslin.
- Add simulation and synthesis scripts for the example.
- Add the documentation of the AES-128 example.
Update README.md.

- Update the README.md for the AES-128 design.
- Add some images for the README.md.