Update changelog and notes

CHANGELOG.md

@@ -8,6 +8,15 @@ This project uses [*towncrier*](https://towncrier.readthedocs.io/) and the chang
 
 <!-- towncrier release notes start -->
 
+## [1.21.0] - 2024-08-20
+
+
+### Changed
+
+- Make description editable
+ ([#811](https://github.com/Uninett/Argus/issues/811))
+
+
 ## [1.20.1] - 2024-07-26
 
 ### Fixed
@@ -56,8 +65,8 @@ moved to a new app, argus.filter
 ### Fixed
 
 - Removed one cause for spurious failures of tests
-- Show infinite end_time as 'Still open' instead of datetime representation in
- email ([#793](https://github.com/Uninett/Argus/issues/793))
+- Show infinite `end_time` as 'Still open' instead of datetime representation
+ in email ([#793](https://github.com/Uninett/Argus/issues/793))
 - Temporarily hide DestinationConfig from User admin in order to allow updating
  Users again. Undo if Django starts allowing JSONFields in UniqueConstraints.
  ([#822](https://github.com/Uninett/Argus/issues/822))

NOTES.md

@@ -3,6 +3,16 @@
 This file documents changes to Argus that are relevant for operations and
 end-users.
 
+## [1.21.0] - 2024-08-20
+
+The "description" field on Incident is now editable via API.
+
+## [1.20.0] - 2024-07-25
+
+This moved around *a lot* of code in order to allow swapping out the filtering
+system. The Filter-model is still used but the bits that uses the contents of
+Filter.filter is independent of the model.
+
 ## [1.19.2] - 2024-05-28
 
 Optimization of API Incident PUT/PATCH.