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>
This adds two new methods to the `App` struct:
- `ToMarkdown`: creates a markdown documentation string
- `ToMan`: creates a man page string
Signed-off-by: Sascha Grunert <mail@saschagrunert.de>