Add a quick start section in the documentation and simplify the configuration file loading mechanism in the cli
CLI config file: keep only 3 situations:
- if the --config-file option is given, load the given file from the given path, otherwise
- if SWH_CONFIG_FILENAME is set, laod this file, otherwise
- use the default config (hard written in the code).
No more config merging nor looking in several default directories. Keep it simple to use and document.
Depends on !66 (closed).
Migrated from D6031 (view on Phabricator)