fix(docs): add v2.9 release schedule

Signed-off-by: Joanna Farley <Joanna.Farley@arm.com>
Change-Id: I082461d7d21f63e3b8cbee37e8f01b8128e4b5a0
diff --git a/docs/about/release-information.rst b/docs/about/release-information.rst
index cb2b883..dead4f7 100644
--- a/docs/about/release-information.rst
+++ b/docs/about/release-information.rst
@@ -52,6 +52,8 @@
 +-----------------+---------------------------+------------------------------+
 | v2.8            | 5th week of Nov '22       | 3rd week of Nov '22          |
 +-----------------+---------------------------+------------------------------+
+| v2.9            | 1st week of May '23       | 3rd week of Apr '23          |
++-----------------+---------------------------+------------------------------+
 
 Removal of Deprecated Interfaces
 --------------------------------