docs: Capitalize title in Supported Images

Capitalize the title to match other chapter titles.

Signed-off-by: Marta Rybczynska <marta.rybczynska@huawei.com>

docs/supported-images.rst

@@ -4,7 +4,7 @@
 
 .. include:: definitions.rst
 
-Supported images
+Supported Images
 ################
 
 To create a custom Linux distribution to match the product requirements,