Fill in release date for 5.1.1

CHANGELOG.txt

@@ -17,8 +17,8 @@ Changelog
  * Maintenance: Add `WagtailTestUtils.get_soup()` method to get a `BeautifulSoup` object from an `HttpResponse` object (Storm Heg)
 
 
-5.1.1 (xx.xx.xxxx) - IN DEVELOPMENT
-~~~~~~~~~~~~~~~~
+5.1.1 (14.08.2023)
+~~~~~~~~~~~~~~~~~~
 
  * Introduce `wagtail.admin.ui.tables.BooleanColumn` to display boolean values as icons (Sage Abdullah)
  * Fix: Show not-`None` falsy values instead of blank in generic table cell template (Sage Abdullah)

docs/releases/5.1.1.md

@@ -1,6 +1,6 @@
-# Wagtail 5.1.1 release notes - IN DEVELOPMENT
+# Wagtail 5.1.1 release notes
 
-_Unreleased_
+_August 14, 2023_
 
 ```{contents}
 ---
@@ -20,11 +20,3 @@ depth: 1
 
  * Show not-`None` falsy values instead of blank in generic table cell template (Sage Abdullah)
  * Fix `read_only` panels for fields with translatable choice labels (Florent Lebreton)
-
-### Documentation
-
- * ...
-
-### Maintenance
-
- * ...