Fix spelling errors

README.rst

dev/gen_typed_stubs.py

dev/poc/jsonargparse_scriptconfig_poc.py

dev/setup_secrets.sh

docs/source/conf.py

docs/source/manual/getting_started.rst

scriptconfig/argparse_ext.py

scriptconfig/config.py

scriptconfig/dataconfig.py

scriptconfig/modal.py

scriptconfig/smartcast.py

scriptconfig/util/util_class.py

scriptconfig/util/util_exception.py