docs: use real field shapes in the write_resource examples

The README's worked example and services.yaml's field example both wrote
`x.com.samsung.da.mode: "Bake"` to /mode/vs/0 -- singular, and a bare
string. That resource takes `modes` as an array (issue #300's own dump
shows `["NoOperation"]`), so both examples were a shape the device would
have ignored, in the one place a user is most likely to copy from. The
README's other two steps were invented the same way; replaced with the
mode -> state: Run sequence issue #300 is actually trying to prove out.

Also adds a short note that payloads go out verbatim, so field names and
types have to match what the resource really uses, pointing at
read_resource with no href as the way to check first -- and aligns the
two new Repo layout rows with the column their neighbors use.

custom_components/localthings/services.yaml

@@ -24,8 +24,8 @@ write_resource:
         (0-30, default 0).
       required: true
       example: >-
-        [{"href": "/mode/vs/0", "payload": {"x.com.samsung.da.mode":
-        "Bake"}, "settle": 3}]
+        [{"href": "/mode/vs/0", "payload": {"x.com.samsung.da.modes":
+        ["Bake"]}, "settle": 3}]
       selector:
         object:
     verify_after: