Explain the explanation about file versions

This explanation looked like it was part of the error. Added an
extra new line and a bit of copy to explain the explanation.

Signed-off-by: Ben Firshman <[email protected]>

compose/config/errors.py

@@ -3,10 +3,11 @@ from __future__ import unicode_literals
 
 
 VERSION_EXPLANATION = (
-    'Either specify a version of "2" (or "2.0") and place your service '
-    'definitions under the `services` key, or omit the `version` key and place '
-    'your service definitions at the root of the file to use version 1.\n'
-    'For more on the Compose file format versions, see '
+    'You might be seeing this error because you\'re using the wrong Compose '
+    'file version. Either specify a version of "2" (or "2.0") and place your '
+    'service definitions under the `services` key, or omit the `version` key '
+    'and place your service definitions at the root of the file to use '
+    'version 1.\nFor more on the Compose file format versions, see '
     'https://docs.docker.com/compose/compose-file/')
 
 

compose/config/validation.py

@@ -219,7 +219,7 @@ def handle_error_for_schema_with_id(error, path):
             return get_unsupported_config_msg(path, invalid_config_key)
 
         if not error.path:
-            return '{}\n{}'.format(error.message, VERSION_EXPLANATION)
+            return '{}\n\n{}'.format(error.message, VERSION_EXPLANATION)
 
 
 def handle_generic_error(error, path):