Config file created by lektord if needed

The config file ~/.config/lektor/lektor.ini must be created by lektor if it doesn't exists. The step needed by the user to create it manually is just confusing.

added Improvement label

mentioned in merge request !117 (merged)

created merge request !117 (merged) to address this issue

closed via merge request !117 (merged)

mentioned in commit 7f535d61