Group all query plan operators (#1122)

Author: JPryce-Aklundh

modules/ROOT/pages/planning-and-tuning/execution-plans.adoc

@@ -71,7 +71,7 @@ image::patterns_qpp_solutions.svg[width="700",role="middle"]
 
 For the purposes of understanding Cypher execution plans, however, the query result is less interesting than the planning that produces it.
 
-[[runtimes-reading-execution-plans]]
+[[reading-execution-plans]]
 == Reading execution plans
 
 The Cypher planner produces logical plans which describe how a particular query is going to be executed.