Add date on the 0.26.0.post1 release notes (#2075)

Kludex · web-flow · commit ada845cc8ad0 · 2023-03-10T10:58:25.000+01:00
diff --git a/docs/release-notes.md b/docs/release-notes.md
@@ -1,5 +1,7 @@
 ## 0.26.0.post1
 
+March 9, 2023
+
 ### Fixed
 * Replace reference from Events to Lifespan on the mkdocs.yml [#2072](https://github.com/encode/starlette/pull/2072).
 
