Whether the Mattermost config.json is writeable by Mattermost.
Most of the settings can be edited in the system console of Mattermost if this option is enabled. A template config using the options specified in services.mattermost will be generated but won't be overwritten on changes or rebuilds.
If this option is disabled, changes in the system console won't be possible (default). If an config.json is present, it will be overwritten!