global: Use proper project name U-Boot

Use proper project name in comments, Kconfig, readmes.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/0dbdf0432405c1c38ffca55703b6737a48219e79.1684307818.git.michal.simek@amd.com
diff --git a/doc/usage/cmd/source.rst b/doc/usage/cmd/source.rst
index 61a4505..a5c5204 100644
--- a/doc/usage/cmd/source.rst
+++ b/doc/usage/cmd/source.rst
@@ -161,7 +161,7 @@
 
     mkimage -T script -n 'Test script' -d boot.txt boot.scr
 
-The script can be execute in U-boot like this:
+The script can be execute in U-Boot like this:
 
 .. code-block::