Doc: Cleanup Sphinx config file
Doc: Cleanup Sphinx config file

- Add a license header
- Explicitly specify language
- Remove unused HTML help section
- Reorganize some commands around the version number generation

AmbiML/ibex,lowRISC/ibex,AmbiML/ibex,AmbiML/ibex,AmbiML/ibex,lowRISC/ibex,lowRISC/ibex,lowRISC/ibex