Add guideline for using safe operator. (#912)

Add guideline for using safe operator

Author: Gauravpurohit409

README.adoc

@@ -323,6 +323,34 @@ foo&. bar
 foo&.bar
 ----
 
+=== Safe navigation
+
+Avoid chaining of `&.`. 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
+
+#good 
+user && user.address.zip
+----
+
+If such a change introduces excessive conditional logic, consider other approaches, such as delegation:
+[source, ruby]
+----
+#bad
+user && user.address && user.address.zip
+
+#good
+class User
+  def zip
+    address&.zip
+  end
+end
+user&.zip
+----
 === Spaces and Braces [[spaces-braces]]
 
 No spaces after `(`, `[` or before `]`, `)`.