expo: Move cedit theme under bootstd

This is related to standard boot, so put it under the same node. This may
simplify schema upstreaming later.

Mention themes in the documentation while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/dts/sandbox.dtsi b/arch/sandbox/dts/sandbox.dtsi
index 8aaf911..ff7e558 100644
--- a/arch/sandbox/dts/sandbox.dtsi
+++ b/arch/sandbox/dts/sandbox.dtsi
@@ -16,12 +16,6 @@
 		stdout-path = "/serial";
 	};
 
-	cedit-theme {
-		font-size = <30>;
-		menu-inset = <3>;
-		menuitem-gap-y = <1>;
-	};
-
 	alarm_wdt: alarm-wdt {
 		compatible = "sandbox,alarm-wdt";
 		timeout-sec = <5>;
@@ -36,6 +30,12 @@
 	bootstd {
 		compatible = "u-boot,boot-std";
 		filename-prefixes = "./";
+
+		cedit-theme {
+			font-size = <30>;
+			menu-inset = <3>;
+			menuitem-gap-y = <1>;
+		};
 	};
 
 	buttons {
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index f351d5c..084cb88 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -100,6 +100,12 @@
 			menuitem-gap-y = <1>;
 		};
 
+		cedit-theme {
+			font-size = <30>;
+			menu-inset = <3>;
+			menuitem-gap-y = <1>;
+		};
+
 		/*
 		 * This is used for the VBE OS-request tests. A FAT filesystem
 		 * created in a partition with the VBE information appearing
@@ -144,12 +150,6 @@
 	cedit: cedit {
 	};
 
-	cedit-theme {
-		font-size = <30>;
-		menu-inset = <3>;
-		menuitem-gap-y = <1>;
-	};
-
 	fuzzing-engine {
 		compatible = "sandbox,fuzzing-engine";
 	};
diff --git a/cmd/cedit.c b/cmd/cedit.c
index 5f0e844..e98121b 100644
--- a/cmd/cedit.c
+++ b/cmd/cedit.c
@@ -65,7 +65,7 @@
 		return CMD_RET_FAILURE;
 	}
 
-	node = ofnode_path("/cedit-theme");
+	node = ofnode_path("/bootstd/cedit-theme");
 	if (ofnode_valid(node)) {
 		ret = expo_apply_theme(cur_exp, node);
 		if (ret)
diff --git a/doc/develop/cedit.rst b/doc/develop/cedit.rst
index 48262ee..8f0a554 100644
--- a/doc/develop/cedit.rst
+++ b/doc/develop/cedit.rst
@@ -145,3 +145,10 @@
 Expo supports multiple scenes but has no pre-determined way of moving between
 them. You could use selection of a menu item as a signal to change the scene,
 but this is not currently implemented in the cedit code (see `cedit_run()`).
+
+
+Themes
+------
+
+The configuration editor uses simple expo themes. The theme is read from
+`/bootstd/cedit-theme` in the devicetree.