[daYamlEditorPlugin] Improve and correct the README
[daYamlEditorPlugin] Improve and correct the README

git-svn-id: e61dbe19c2083c9acf1cdf717e259e7deabbc0ba@27227 ee427ae8-e902-0410-961c-c3ed070cd9f9

Symfony-Plugins/daYamlEditorPlugin