doc: release: 3.5: (partial) kernel release notes

Include dynamic thread stack allocation and support for
k_spin_trylock().

(cherry picked from commit 9cd81c1)

Original-Signed-off-by: Christopher Friedt <cfriedt@meta.com>
GitOrigin-RevId: 9cd81c1
Change-Id: I57561a19f77abc803517747ac4fe7df9bbe7379f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/4921898
Reviewed-by: Keith Short <keithshort@chromium.org>
Tested-by: Keith Short <keithshort@chromium.org>
Commit-Queue: Keith Short <keithshort@chromium.org>
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>

doc/releases/release-notes-3.5.rst

@@ -47,6 +47,9 @@ https://docs.zephyrproject.org/latest/security/vulnerabilities.html
 Kernel
 ******
 
+* Added support for dynamic thread stack allocation via :c:func:`k_thread_stack_alloc`
+* Added support for :c:func:`k_spin_trylock`
+
 Architectures
 *************