releases.rst: mark 5.15 as LTS

For now make it 2 years, until companies agree that they are
going to use this thing and need it supported longer.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/content/releases.rst b/content/releases.rst
index acfdd3c..ace67f5 100644
--- a/content/releases.rst
+++ b/content/releases.rst
@@ -40,6 +40,7 @@
     ======== ================================ ============ ==================
     Version  Maintainer                       Released     Projected EOL
     ======== ================================ ============ ==================
+    5.15     Greg Kroah-Hartman & Sasha Levin 2021-10-31   Oct, 2023
     5.10     Greg Kroah-Hartman & Sasha Levin 2020-12-13   Dec, 2026
     5.4      Greg Kroah-Hartman & Sasha Levin 2019-11-24   Dec, 2025
     4.19     Greg Kroah-Hartman & Sasha Levin 2018-10-22   Dec, 2024