(GH-170) Add warning for not using yaml config

Author: gep13

Source/GitReleaseManager/Configuration/ConfigurationProvider.cs

@@ -42,6 +42,8 @@ public static Config Provide(string gitDirectory, IFileSystem fileSystem)
                 }
             }
 
+            _logger.Warning("Yaml not found, that's ok! Learn more at {Url}", "https://gittools.github.io/GitReleaseManager/docs/yaml");
+
             _logger.Verbose("No configuration file was found. Loading default configuration.");
 
             return new Config();
@@ -111,4 +113,4 @@ private static void EnsureDefaultConfig(Config configuration)
             }
         }
     }
-}
+}