Move snippets outside of markdown

Signed-off-by: Helder Correia <174525+helderco@users.noreply.github.com>

docs/tests/core-concepts/client/plans/cmd.cue

@@ -0,0 +1,18 @@
+dagger.#Plan & {
+	client: commands: {
+		os: {
+			name: "uname"
+			args: ["-s"]
+		}
+		arch: {
+			name: "uname"
+			args: ["-m"]
+		}
+	}
+
+	actions: build: go.#Build & {
+		os:   client.commands.os.stdout
+		arch: client.commands.arch.stdout
+		// ...
+	}
+}