Provide direction to users of the now deprecated class FileUriResolver

pkg/analyzer/lib/src/generated/source_io.dart

Index: pkg/analyzer/lib/src/generated/source_io.dart
diff --git a/pkg/analyzer/lib/src/generated/source_io.dart b/pkg/analyzer/lib/src/generated/source_io.dart
index 5414d83b910c03291228df8175bfc8efca2be974..f7b47ef5ede0314dbe2500c09b060932c7eff9ec 100644
--- a/pkg/analyzer/lib/src/generated/source_io.dart
+++ b/pkg/analyzer/lib/src/generated/source_io.dart
@@ -262,6 +262,9 @@ class FileBasedSource extends Source {
 
 /**
  * Instances of the class `FileUriResolver` resolve `file` URI's.
+ *
+ * This class is now deprecated, 'new FileUriResolver()' is equivalent to
+ * 'new ResourceUriResolver(PhysicalResourceProvider.INSTANCE)'.
  */
 @deprecated
 class FileUriResolver extends UriResolver {
@@ -517,6 +520,10 @@ class PackageUriResolver extends UriResolver {
 
 /**
  * Instances of the class `RelativeFileUriResolver` resolve `file` URI's.
+ *
+ * This class is now deprecated, file URI resolution should be done with
+ * ResourceUriResolver, i.e.
+ * 'new ResourceUriResolver(PhysicalResourceProvider.INSTANCE)'.
  */
 @deprecated
 class RelativeFileUriResolver extends UriResolver {