clarify cardinality nuance

Author: JPryce-Aklundh

modules/ROOT/pages/patterns/shortest-paths.adoc

@@ -779,7 +779,7 @@ ready to start consuming query after 40 ms, results consumed after another 331 m
 
 If the query is rewritten with a `CALL` subquery the planner will use `StatefulShortestPath(Into)` which performs separate traversals for each individual source-target node pairs.
 
-.Multi-target shortest path query rewritten with a CALL subquery
+.Multi-target shortest path query rewritten with a `CALL` subquery
 [source, cypher]
 ----
 PROFILE
@@ -840,8 +840,8 @@ a| Used when:
 
 * The xref:patterns/reference.adoc#shortest-functions[`shortestPath()` or `allShortestPaths()`] functions are used.
 
-Or, if the planner estimates a single source-target node pair and the following are all true:
-
+Or, when the estimated cardinality of the source and target nodes in a shortest path are 1 or less and the following are all true:
+ 
 * Selector is one of: `SHORTEST 1`, `ANY`, `ANY SHORTEST`, `ALL SHORTEST`, `SHORTEST GROUP`, or `SHORTEST 1 GROUP`.
 * There is only one relationship pattern.
 * If the pattern is a xref:patterns/variable-length-patterns.adoc#quantified-path-patterns[quantified path pattern] in the form of `\(()-[]-())`, or is a  xref:patterns/variable-length-patterns.adoc#quantified-relationship[quantified-relationship], and it uses a filter that can be applied directly to the relationship.
@@ -850,7 +850,7 @@ Or, if the planner estimates a single source-target node pair and the following
 | `StatefulShortestPath(Into)`
 | Performs bidirectional BFS from target and source node.
 Terminates when a shortest path is found between them.
-a| Used when the planner estimates a single source-target node pair in a shortest path and either of the following are true:
+a| Used when the estimated cardinality of the source and target nodes in a shortest path are 1 or less and either of the following are true:
 
 * Selector is one of: `ANY/SHORTEST k` or `SHORTEST k GROUPS` and `k` is larger than `1`.
 * There is more than one relationship pattern.