Fix typo: preceeding -> preceding

Author: mr-c

Workflow.yml

@@ -654,7 +654,7 @@ $graph:
     those steps.  When a step produces output that will be consumed by a
     second step, the first step is a dependency of the second step.
 
-    When there is a dependency, the workflow engine must execute the preceeding
+    When there is a dependency, the workflow engine must execute the preceding
     step and wait for it to successfully produce output before executing the
     dependent step.  If two steps are defined in the workflow graph that
     are not directly or indirectly dependent, these steps are **independent**,