Hi,

In gbp-buildpackage(1)'s EXAMPLES, there says:

	Build a source-only package that can be signed and uploaded to Debian:
		gbp buildpackage -S -d

However with:

	[buildpackage]
	builder = sbuild

Running that returns:

	gbp:info: Performing the build
	Unknown option: S
	Option d requires an argument
	E: Error parsing command-line options
	I: Run 'sbuild --help' to list usage example and all available options
	gbp:error: 'sbuild -S -d' failed: it exited with 1

This is more a manpage thing, there seems to have more accurate examples
on the wiki's SourceOnlyUpload page.

https://wiki.debian.org/SourceOnlyUpload#Generating__source.changes_with_git-buildpackage_tool_chain

Also, gbp-buildpackage(1) only documents pbuilder, not sbuild. Please
consider adding them.

Thanks!