docs: distinguish the partial render from the empty one in the showcase

The README claimed both showcase tools rendered nothing but the Execute Tool
button, which the PR's own screenshots contradict: `echo` carries a root
`message` and rendered that one field, so it was callable with half its
arguments; only `get_weather`, whose fields live entirely on its `oneOf`,
rendered no controls at all. The two now show the two halves deliberately.

Signed-off-by: cliffhall <cliff@futurescale.com>

Author: cliffhall

README.md

@@ -296,7 +296,9 @@ The **TUI** had the same gap and is worth checking against the same server (`--t
 
 The 2026-07-28 revision makes this shape explicitly legal: `type: "object"` is required at the root, and beyond that "any JSON Schema 2020-12 keyword may appear alongside `type`, including composition keywords (`oneOf`, `anyOf`, `allOf`, `not`)".
 
-Open the Tools tab and select `echo`. Above the fields is a **Variant** picker listing the union's alternatives — labelled from each branch's `title`, else its discriminator `const`, else its position — and choosing one swaps in that branch's fields with the discriminator already filled in. On the broken build both tools rendered **nothing but the Execute Tool button**: no picker, no fields, not even the raw-JSON editor a union-typed _property_ falls back to, so neither tool could be called with anything but empty arguments ([#2123](https://github.com/modelcontextprotocol/inspector/issues/2123)).
+Open the Tools tab and select `echo`. Above the fields is a **Variant** picker listing the union's alternatives — labelled from each branch's `title`, else its discriminator `const`, else its position — and choosing one swaps in that branch's fields with the discriminator already filled in.
+
+The two tools show the two halves of the old behavior. On the broken build `echo` rendered its root `message` and **nothing from either branch**, so it could only ever be called with half its arguments; `get_weather`, whose fields live entirely on its `oneOf`, rendered **nothing but the Execute Tool button** — no picker, no fields, not even the raw-JSON editor a union-typed _property_ falls back to ([#2123](https://github.com/modelcontextprotocol/inspector/issues/2123)).
 
 Switching branches drops the values that belonged to the outgoing one. They are no longer on screen, so the user can neither see nor clear them, and submitting them would describe a shape the call is not making.