I can't find any documentation on the Web Flow support in IDE/STS.

In the STS Help (2.3.0.RELEASE) the help link for "Web Flow Support" is
http://springide.org/doc/SWF

But it is does not exist (404 error) and there is an open defect for that:
http://jira.springframework.org/browse/IDE-1076

Apparently there used to be a wiki on springide.org.

This issue refers to a wiki page named "WebFlowEditorUsage" which does not exist anymore:
http://issues.springframework.org/browse/IDE-503

Both of these URLs give me a 404:
http://springide.org/project/wiki/WebFlowEditor
http://springide.org/project/wiki/WebFlowEditorUsage

I wonder what happened? Is there no documentation for the current Web Flow support in the Spring IDE / STS?