Update changelogs for 2.5.2 release

Author: Ed Slavich

CHANGES.rst

@@ -1,9 +1,4 @@
-2.6.0 (unreleased)
-------------------
-
-- AsdfDeprecationWarning now subclasses DeprecationWarning. [#710]
-
-2.5.2 (unreleased)
+2.5.2 (2020-02-28)
 ------------------
 
 - Add a developer overview document to help understand how ASDF works

docs/asdf/changes.rst

@@ -4,14 +4,26 @@
 Changes
 *******
 
+What's New in ASDF 2.5.2?
+=========================
+
+The ASDF Standard is at v1.4.0.
+
+Changes include:
+
+* Add schemas that were previously missing from ASDF Standard 1.4.0,
+  and fix a variety of minor issues in ``AsdfType`` subclasses.
+
+* Add general and versioning-specific developer documentation.
+
 What's New in ASDF 2.5.1?
 =========================
 
 The ASDF Standard is at v1.4.0.
 
 Changes include:
 
-- Fix bug in test causing failure when test suite is run against
+* Fix bug in test causing failure when test suite is run against
   an installed asdf package.
 
 What's New in ASDF 2.5.0?