Spark support (docs link is broken)

[matanox]

The docs are really nice. I wonder what kind of support for Spark might be helpful, however in ―

For distributed execution, support for running pipelines using Apache Spark can be found in the spark sub-project

the hyperlink seems to be broken. Was there something specific for Spark which is now removed?
Link to the quoted docs page - https://github.com/allenai/pipeline/blob/master/docs/ParallelExecution.md