Update doctrine.rst

sergiosusa · javiereguiluz · commit 3db34d4956bc · 2018-05-25T08:54:36.000+02:00
just adding some quotes to server_version, couple of lines before is explained this: 

"Always wrap the server version number with quotes to parse it as a string instead of a float number"
diff --git a/reference/configuration/doctrine.rst b/reference/configuration/doctrine.rst
@@ -389,13 +389,13 @@ If you want to configure multiple connections in YAML, put them under the
                     user:             root
                     password:         null
                     host:             localhost
-                    server_version:   5.6
+                    server_version:   '5.6'
                 customer:
                     dbname:           customer
                     user:             root
                     password:         null
                     host:             localhost
-                    server_version:   5.7
+                    server_version:   '5.7'
 
 The ``database_connection`` service always refers to the *default* connection,
 which is the first one defined or the one configured via the
