update install. fix doc errors

- [x] Is it mergable
- [N/A] Did it pass the tests?
- [N/A] If it introduce new functionality in scripts/ is it tested? Check for code coverage
- [X] Is it well formatted? Look at `pep8`/`pylint` and `cppcheck` output. Use `autopep8` and `astyle -A10` if needed. 
- [ ] Is it documented in the Changelog?