Make validation error less robotic

"ERROR: Validation failed in file './docker-compose.yml', reason(s):"

is now:

"ERROR: The Compose file './docker-compose.yml' is invalid because:"

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

compose/config/validation.py

@@ -416,6 +416,6 @@ def handle_errors(errors, format_error_func, filename):
 
     error_msg = '\n'.join(format_error_func(error) for error in errors)
     raise ConfigurationError(
-        "Validation failed{file_msg}, reason(s):\n{error_msg}".format(
-            file_msg=" in file '{}'".format(filename) if filename else "",
+        "The Compose file{file_msg} is invalid because:\n{error_msg}".format(
+            file_msg=" '{}'".format(filename) if filename else "",
             error_msg=error_msg))