Extend safe navigation docs about long &. chains

README.adoc

@@ -325,32 +325,33 @@ foo&.bar
 
 === Safe navigation
 
-Avoid chaining of `&.`. Replace with `.` and an explicit check.
+Avoid chains of `&.` longer than two. Replace with `.` and an explicit check.
 E.g. if users are guaranteed to have an address and addresses are guaranteed to have a zip code:
 
 [source,ruby]
 ----
 # bad
-user&.address&.zip
+user&.address&.zip&.upcase
 
 # good
-user && user.address.zip
+user && user.address.zip.upcase
 ----
 
 If such a change introduces excessive conditional logic, consider other approaches, such as delegation:
 [source,ruby]
 ----
 # bad
-user && user.address && user.address.zip
+user && user.address && user.address.zip && user.address.zip.upcase
 
 # good
 class User
   def zip
     address&.zip
   end
 end
-user&.zip
+user&.zip&.upcase
 ----
+
 === Spaces and Braces [[spaces-braces]]
 
 No spaces after `(`, `[` or before `]`, `)`.