Add a clearer deprecation message for replacing the user of paths in the size() function. (#515)

Size() cannot accept a path anymore (as of 4.0), but can take pattern
comprehension and could now be replaced with 5.0 feature, COUNT. This PR
makes this replacement clearer to the users.

Author: gem-neo4j

modules/ROOT/pages/deprecations-additions-removals-compatibility.adoc

@@ -3271,7 +3271,18 @@ label:restricted[]
 size()
 ----
 a|
-No longer works for paths. Only works for strings, lists and pattern expressions. See xref:functions/scalar.adoc#functions-size[size()] for more details.
+Only works for strings, lists and pattern comprehensions, and no longer works for paths.
+For versions above 5.0, use a `COUNT` expression instead:
+[source, cypher, role="noheader"]
+----
+RETURN COUNT { (a)-[]->(b) }
+----
+For versions below 5.0, use a pattern comprehension instead:
+[source, cypher, role="noheader"]
+----
+RETURN size([ (a)-[]->(b) \| a ])
+----
+See xref:functions/scalar.adoc#functions-size[size()] and xref:syntax/expressions.adoc#count-subqueries[Count Subqueries] for more details.
 |===
 
 === Updated features