minor #17 Proposed a help note for the DB_URL config format (javiereguiluz)

This PR was squashed before being merged into the master branch (closes #17).

Discussion
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Proposed a help note for the DB_URL  config format

I'm not sure about this, but given that the URL format is so new to most developers, should we add a help note like this one?

Commits
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193b15b Proposed a help note for the DB_URL  config format

doctrine/doctrine-bundle/1.6/manifest.json

@@ -7,7 +7,8 @@
         "src/": "%SRC_DIR%/"
     },
     "env": {
-        "#1": "For a sqlite database, use: \"sqlite:///%kernel.project_dir%/var/data.db\"",
+        "#1": "DB_URL format: \"vendor://username:password@host-or-ip:port/database-name?optional=config\"",
+        "#2": "For a sqlite database, use: \"sqlite:///%kernel.project_dir%/var/data.db\"",
         "DATABASE_URL": "mysql://root@127.0.0.1:3306/symfony?charset=utf8mb4"
     },
     "aliases": ["doctrine", "orm"]