Apply suggestions from code review

Co-authored-by: Cody Goldberg <cody@goldberg.fyi>

Author: kevmoo

gcp/lib/src/metadata.dart

@@ -81,11 +81,8 @@ enum MetadataValue {
     return result;
   }
 
-  /// Returns the
-  /// [Region](https://cloud.google.com/compute/docs/regions-zones#identifying_a_region_or_zone)
-  /// for the current instance by checking the environment variables in
-  /// [environmentValues].
-  ///
+  /// Returns a metadata value for the current instance by checking the
+  /// environment variables in [environmentVariables].
   /// The list is checked in order. This is useful for local development.
   ///
   /// If no matching variable is found, `null` is returned.
@@ -98,10 +95,8 @@ enum MetadataValue {
     return null;
   }
 
-  /// Returns a [Future] that completes with the
-  /// [Region](https://cloud.google.com/compute/docs/regions-zones#identifying_a_region_or_zone)
-  /// for the current instance by checking
-  /// [instance metadata](https://cloud.google.com/compute/docs/metadata/default-metadata-values#vm_instance_metadata).
+  /// Returns a [Future] that completes with a metadata value for the current
+  /// instance by contacting the metadata server.
   ///
   /// If the metadata server cannot be contacted, a [BadConfigurationException]
   /// is thrown.