Fix Sphinx warnings (QasmLexer tokens, static)
Fix Sphinx warnings (QasmLexer tokens, static)

* Prevent Sphinx from interpreting the matching of the QasmLexer Tokens
  as regular docstrings by listening to the `autodoc-process-docstring`
  event.
* Remove unreachable path in the `html_static_path` variable.

atilag/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,atilag/qiskit-sdk-py,atilag/qiskit-sdk-py,QISKit/qiskit-sdk-py