update styleguide with cypherfmt rules

Author: tomasnyberg

modules/ROOT/pages/styleguide.adoc

@@ -9,6 +9,12 @@ The purpose of the Cypher styleguide is to make queries as easy to read as possi
 
 For rules and recommendations for naming of labels, relationship types and properties, please see the xref::syntax/naming.adoc[Naming rules and recommendations].
 
+The best way to make sure your queries follow the styling rules is to use `cypherfmt`, the official Cypher formatter.
+It is available as part of the https://marketplace.visualstudio.com/items?itemName=neo4j-extensions.neo4j-for-vscode[Neo4j VS Code Extension],
+and as a command line tool through the https://www.npmjs.com/package/@neo4j-cypher/language-support[Neo4j Cypher Language Support npm package].
+
+
+
 [[cypher-styleguide-general-recommendations]]
 == General recommendations
 
@@ -115,6 +121,123 @@ WHERE EXISTS { (a)-->(b:B) }
 RETURN a.prop
 ----
 
+* Limit line length to 80 characters if possible. Line breaks should be applied starting from the outermost group, with each nested group breaking
+until either the line fits or no more line breaks can be inserted. Add two spaces of indentation for each nested broken group.
+
+.Bad
+[source, cypher]
+----
+MATCH (n)
+WHERE n.prop <> 'a' AND n.prop <> 'b' AND n.prop <> 'c' AND n.prop <> 'd' AND n.prop <> 'e'
+RETURN n
+----
+
+.Good
+[source, cypher]
+----
+MATCH (n)
+WHERE
+  n.prop <> 'a' AND
+  n.prop <> 'b' AND
+  n.prop <> 'c' AND
+  n.prop <> 'd' AND
+  n.prop <> 'e'
+RETURN n
+----
+
+* Start ORDER BY and LIMIT clauses on new lines.
+
+.Bad
+[source, cypher]
+----
+MATCH (n)
+RETURN 5 ORDER BY n.prop LIMIT 10
+----
+
+.Good
+[source, cypher]
+----
+MATCH (n)
+RETURN 5
+ORDER BY n.prop
+LIMIT 10
+----
+
+* A group containing a CASE expression should always split, and each WHEN, ELSE, and END should be put on a new line. Additionally, WHEN and ELSE should add two spaces of indentation.
+
+.Bad
+[source, cypher]
+----
+MATCH (n:Person {name: 'Alice'})
+RETURN CASE WHEN n.age >= 18 THEN 'Adult' ELSE 'Minor' END AS ageGroup
+----
+
+.Good
+[source, cypher]
+----
+MATCH (n:Person {name: 'Alice'})
+RETURN
+  CASE
+    WHEN n.age >= 18 THEN 'Adult'
+    ELSE 'Minor'
+  END AS ageGroup-
+----
+
+* Lines that end with a list or map literal and do not fit within the maximum width should leave
+the opening bracket/brace on the previous line and use only two additional spaces of indentation.
+
+.Bad
+[source, cypher]
+----
+RETURN 
+  [
+    "Alice",
+    "Bob",
+    "Charlie",
+    "David",
+    "Eve",
+    "Frank",
+    "Grace",
+    "Heidi",
+    "Ivan",
+    "Judy"
+  ]
+----
+
+.Good
+[source, cypher]
+----
+RETURN [
+  "Alice",
+  "Bob",
+  "Charlie",
+  "David",
+  "Eve",
+  "Frank",
+  "Grace",
+  "Heidi",
+  "Ivan",
+  "Judy"
+]
+----
+
+* A single blank line may be used to separate clauses, queries or comments.
+
+.Good
+[source, cypher]
+----
+MATCH (n)--[r]->(m)
+RETURN n, r, m
+----
+
+.Also good
+[source, cypher]
+----
+MATCH (n)--[r]->(m)
+
+RETURN n, r, m
+----
+
 [[cypher-styleguide-casing]]
 == Casing