diff --git a/docs/install/release_notes.md b/docs/install/release_notes.md
index 7b7959d..4a50b6f 100644
--- a/docs/install/release_notes.md
+++ b/docs/install/release_notes.md
@@ -3,67 +3,78 @@
 
 # Release notes
 
+(release-0-21)=
+## 0.21 *(2024-11-23)*
+
+- Added the {rst:dir}`defaults` directive.
+- Fixed a cosmetic issue with collapsed admonitions.
+
 (release-0-20)=
 ## 0.20 *(2024-11-21)*
 
-- Added the `num` role for generic numbering.
+- Added the {rst:role}`num` role.
 
 (release-0-19)=
 ## 0.19 *(2024-11-17)*
 
 - Fixed the un-collapsing of admonitions through click events.
-- Fixed the full-screen mode of `{exec} html`.
+- Fixed the full-screen mode of [`{exec} html`](/demo/html).
 
 (release-0-18)=
 ## 0.18 *(2024-11-14)*
 
-- Added the `youtube` and `iframe` directives.
+- Added the {rst:dir}`youtube` and {rst:dir}`iframe` directives.
 - Removed the dependency on `sphinx_togglebutton`.
 
 (release-0-17)=
 ## 0.17 *(2024-11-09)*
 
-- Added the `solution` directive and the "Toggle solutions" navbar button.
+- Added the {rst:dir}`solution` directive and the "Toggle solutions" navbar
+  button.
 - Fixed the flickering on page load due to `sphinx_togglebutton`.
 - Added an option to exclude files from watching in the dev server.
 
 (release-0-16)=
 ## 0.16 *(2024-11-03)*
 
-- Added support for `{exec} html`.
-- Added support for styling editors and output blocks with `{exec} :style:` and
-  `{exec} :output-style:`.
-- Added the `metadata` directive.
+- Added support for [`{exec} html`](/demo/html).
+- Added support for styling editors and output blocks with
+  {rst:dir}`{exec} :style: <exec:style>` and
+  {rst:dir}`{exec} :output-style: <exec:output-style>`.
+- Added the {rst:dir}`metadata` directive.
 - The rendered HTML output is now fully self-contained.
 
 (release-0-15)=
 ## 0.15 *(2024-10-19)*
 
-- Added a mechanism to render arbitrary HTML from `{exec} python` blocks.
+- Added a mechanism to render arbitrary HTML from
+  [`{exec} python`](/demo/python) blocks.
 - Added a Python module to create SVG images.
-- Added automatic focusing of `{exec} python` text input elements.
+- Added automatic focusing of [`{exec} python`](/demo/python) text input
+  elements.
 - Fixed the positioning of the "Remove" button on scrollable tables.
 
 (release-0-14)=
 ## 0.14 *(2024-10-03)*
 
-- Added a button to remove `{exec}` output.
+- Added a button to remove {rst:dir}`{exec} <exec>` output.
 - Fixed `{exec} :linenos:`.
 
 (release-0-13)=
 ## 0.13 *(2024-09-29)*
 
-- Added support for executing blocks after a block with `{exec} :then:`.
+- Added support for executing blocks after a block with
+  {rst:dir}`{exec} :then: <exec:then>`.
 
 (release-0-12)=
 ## 0.12 *(2024-09-28)*
 
-- Added user input functionality for `{exec} python` blocks.
+- Added user input functionality for [`{exec} python`](/demo/python) blocks.
 
 (release-0-11)=
 ## 0.11 *(2024-09-27)*
 
-- `{exec} python` now works when offline.
+- [`{exec} python`](/demo/python) now works when offline.
 - Fixed an issue that prevented entering the character `/` in editors.
 - Disabled the search shortcut, as it can interfere with editors.
 - Made the workaround for missing `SharedArrayBuffer` configurable.
@@ -75,7 +86,7 @@
 (release-0-10)=
 ## 0.10 *(2024-09-21)*
 
-- Added initial support for `{exec} python`.
+- Added initial support for [`{exec} python`](/demo/python).
   - Currently, Python code execution only works when online.
 - Made the automatic page reloading more reactive.
 - Made pages cross-origin isolated even if the server doesn't set the
@@ -92,13 +103,14 @@ and Safari don't support it (yet).
 ## 0.9 *(2024-09-12)*
 
 - Added automatic page reloading on successful builds in the dev server.
-- Fixed encoding issues with `{exec} :include:`.
+- Fixed encoding issues with {rst:dir}`{exec} :include: <exec:include>`.
 
 (release-0-8)=
 ## 0.8 *(2024-09-12)*
 
-- Allowed multiple references in `{exec} :after:`.
-- Added support for including external files with `{exec} :include:`.
+- Allowed multiple references in {rst:dir}`{exec} :after: <exec:after>`.
+- Added support for including external files with
+  {rst:dir}`{exec} :include: <exec:include>`.
 
 (release-0-7)=
 ## 0.7 *(2024-09-07)*
@@ -108,15 +120,16 @@ and Safari don't support it (yet).
 (release-0-6)=
 ## 0.6 *(2024-09-07)*
 
-- Added support for editable blocks with `{exec} :editable:`.
+- Added support for editable blocks with
+  {rst:dir}`{exec} :editable: <exec:editable>`.
 
 (release-0-5)=
 ## 0.5 *(2024-08-31)*
 
-- Added on-click execution of `exec` blocks.
-- Added support for dependencies with `{exec} :after:`.
-- Added proper rendering of SQL errors in `{exec} sql`.
-- Fixed the handling of `NULL` values in `{exec} sql`.
+- Added on-click execution of {rst:dir}`exec` blocks.
+- Added support for dependencies with {rst:dir}`{exec} :after: <exec:after>`.
+- Added proper rendering of SQL errors in [`{exec} sql`](/demo/sql).
+- Fixed the handling of `NULL` values in [`{exec} sql`](/demo/sql).
 
 (release-0-4)=
 ## 0.4 *(2024-08-22)*
diff --git a/tdoc/common/__init__.py b/tdoc/common/__init__.py
index 60fdd69..71f9692 100644
--- a/tdoc/common/__init__.py
+++ b/tdoc/common/__init__.py
@@ -8,7 +8,7 @@
 from sphinx.util import fileutil, logging
 
 __project__ = 't-doc-common'
-__version__ = '0.21.dev1'
+__version__ = '0.21'
 
 _log = logging.getLogger(__name__)
 _messages = 'tdoc'