Move upgrade instructions from README to UPGRADE file (#166)

README.md

@@ -354,9 +354,7 @@ in your browser and login with the password specified above.
 
 # How do I upgrade CartoDB? #
 
-There's no standard procedure to migrate from one version to another of
-the rails application, so version specific procedures are documented
-in the NEWS.md file.
+See UPGRADE file for instructions about upgrading CartoDB.
 
 For upgrade of Windshaft-CartoDB and CartoDB-SQL-API see the relative
 documentation.

UPGRADE

@@ -1,5 +1,9 @@
-After upgrading the rails code to <version>,
-you must upgrade existing databases using these commands:
+There's no standard procedure to migrate from one version to another of
+the rails application, so version specific procedures are documented
+in the NEWS.md file.
+
+In absence of specific instructions, after upgrading the rails code to
+<version>, you must upgrade existing databases using these commands:
 
 $ bundle exec rake db:migrate
 $ bundle exec rake cartodb:db:load_functions
@@ -8,3 +12,5 @@ $ bundle exec rake cartodb:db:create_importer_schema
 $ bundle exec rake cartodb:db:migrate_to[<version>]
 
 NOTE: rails must be restarted after an upgrade
+
+