doc: update mail author for st-dt.rst

Update author email address with the one dedicated to
upstream activities.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/doc/board/st/st-dt.rst b/doc/board/st/st-dt.rst
index 3dade16..67e16ef 100644
--- a/doc/board/st/st-dt.rst
+++ b/doc/board/st/st-dt.rst
@@ -1,5 +1,5 @@
 .. SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
-.. sectionauthor:: Patrick Delaunay <patrick.delaunay@st.com>
+.. sectionauthor:: Patrick Delaunay <patrick.delaunay@foss.st.com>
 
 U-Boot device tree bindings
 ----------------------------