v1.21 Release

Finish the release notes for the 1.21 release.

Signed-off-by: Zach Brown <zab@versity.com>

ReleaseNotes.md

@@ -1,6 +1,27 @@
 Versity ScoutFS Release Notes
 =============================
 
+---
+v1.21
+\
+*Jul 1, 2024*
+
+This release adds features that rely on incompatible changes to
+structure the file system.  The process of advancing the format version
+to enable these features is described in scoutfs(5).
+
+Added the ".indx." extended attribute tag which can be used to determine
+the sorting of files in a global index.
+
+Added ScoutFS quotas which let rules define file size and count limits
+in terms of ".totl." extended attribute totals.
+
+Added the project ID file attribute which is inherited from parent
+directories on creation.  ScoutFS quota rules can reference project IDs.
+
+Add a retention attribute for files which prevents modification once
+enabled.
+
 ---
 v1.20
 \