Move deprecated image filter headers out of include/ and into src/

Bug: skia:9310
Change-Id: I387f0251f05a2b6f2bc5a759f608d5766ed11ce2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/357285
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Mike Reed <reed@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index b46b79f..595ec0a 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -7,6 +7,10 @@
 Milestone 90
 ------------
 
+  * Remove deprecated SkImageFilter factory functions and supporting types. All default-provided
+    SkImageFilters are now only constructed via 'include/effects/SkImageFilters.h'
+    https://review.skia.org/357285
+
   * Added SkRuntimeEffect::makeImage() to capture the output of an SkRuntimeEffect in an SkImage.
     https://review.skia.org/357284