docs: remove the nonexistent toolName field from tool.execution_complete (#2212)

The Node.js extension-authoring docs listed a `toolName` field on the
`tool.execution_complete` session event, in two event-field reference
tables and three handler code-comments. That event has no `toolName`:
`ToolExecutionCompleteData` declares `required: ["toolCallId","success"]`
with `additionalProperties: false` and no `toolName` property, so reading
`event.data.toolName` in a completion handler is always undefined.
`toolName` is emitted on `tool.execution_start`, and a completion is
correlated to its start by `toolCallId`.

Remove the field from the two `tool.execution_complete` rows and the three
completion-handler comments. It stays on the `tool.execution_start` rows.
The repository's shared event reference in docs/features/streaming-events.md
already documents the event without it.

Co-authored-by: examon <examon@users.noreply.github.com>

Author: examon

nodejs/docs/agent-author.md

@@ -258,7 +258,7 @@ Subscribe to session events. Returns an unsubscribe function.
 
 ```js
 const unsub = session.on("tool.execution_complete", (event) => {
-    // event.data.toolName, event.data.success, event.data.result
+    // event.data.success, event.data.result
 });
 ```
 
@@ -268,7 +268,7 @@ const unsub = session.on("tool.execution_complete", (event) => {
 | ------------------------- | ------------------------------------------------------ |
 | `assistant.message`       | `content`, `messageId`                                 |
 | `tool.execution_start`    | `toolCallId`, `toolName`, `arguments`                  |
-| `tool.execution_complete` | `toolCallId`, `toolName`, `success`, `result`, `error` |
+| `tool.execution_complete` | `toolCallId`, `success`, `result`, `error`             |
 | `user.message`            | `content`, `attachments`, `source`                     |
 | `session.idle`            | `backgroundTasks`                                      |
 | `session.error`           | `errorType`, `message`, `stack`                        |

nodejs/docs/examples.md

@@ -368,7 +368,7 @@ session.on((event) => {
 
 ```js
 const unsubscribe = session.on("tool.execution_complete", (event) => {
-    // event.data.toolName, event.data.success, event.data.result, event.data.error
+    // event.data.success, event.data.result, event.data.error
 });
 
 // Later, stop listening
@@ -417,7 +417,7 @@ session.on("assistant.message", (event) => {
 | `assistant.message`         | Agent's final response                           | `content`, `messageId`, `toolRequests`                 |
 | `assistant.message_delta`   | Message content chunks (ephemeral)               | `deltaContent`                                         |
 | `tool.execution_start`      | A tool is about to run                           | `toolCallId`, `toolName`, `arguments`                  |
-| `tool.execution_complete`   | A tool finished running                          | `toolCallId`, `toolName`, `success`, `result`, `error` |
+| `tool.execution_complete`   | A tool finished running                          | `toolCallId`, `success`, `result`, `error`             |
 | `user.message`              | User sent a message                              | `content`, `attachments`, `source`                     |
 | `session.idle`              | Session finished processing a turn               | `backgroundTasks`                                      |
 | `session.error`             | An error occurred                                | `errorType`, `message`, `stack`                        |
@@ -677,6 +677,6 @@ session.on("assistant.message", (event) => {
 });
 
 session.on("tool.execution_complete", (event) => {
-    // event.data.success, event.data.toolName, event.data.result
+    // event.data.success, event.data.result
 });
 ```