docs(spel): adds a note indicating expressions are based on Spring (#1637)
docs(spel): adds a note indicating expressions are based on Spring (#1637)


ttomsu/spinnaker.github.io,ttomsu/spinnaker.github.io,spinnaker/spinnaker.github.io,spinnaker/spinnaker.github.io,spinnaker/spinnaker.github.io,ttomsu/spinnaker.github.io