Added chained-comparison message example (#6107)

Co-authored-by: Vladyslav Krylasov <vladyslav.krylasov@gmail.com>

Author: matusvalo

doc/data/messages/c/chained-comparison/bad.py

@@ -0,0 +1,5 @@
+a = int(input())
+b = int(input())
+c = int(input())
+if a < b and b < c:  # [chained-comparison]
+    pass

doc/data/messages/c/chained-comparison/good.py

@@ -0,0 +1,5 @@
+a = int(input())
+b = int(input())
+c = int(input())
+if a < b < c:
+    pass