* feat(docs): add UsageText to docs output for markdown and man page generation
* feat(docs): updated tests, DRYd up code, cleaned up string logic
* fix(lint): fixed go1.15 lint errors
This commit adds a new method `ToFishCompletion` to the `*App` which can
be used to generate a fish completion string for the application.
Relates to: #351
Signed-off-by: Sascha Grunert <sgrunert@suse.com>