Points to be added to the recommended practices list

[tobyhodges]

• subworkflow refactoring and levels of abstraction - example wording (from @MarkRobbo here):

CWL implementations which also implement SubworkflowFeatureRequirement can support nesting workflows as a step within others. Complex workflows with individual components which can be abstracted should utilise this to make their workflow modular and allow sections of them to be easily reused

[tobyhodges]

accidentally merged this ( #40 ) without chance for review. Please take a look and let me know if you want me to revert/revise.

[mr-c]

All good, thanks!