Fix typo

Author: susan-shu-c

rfcs/text/0052/gen_ai.yaml

@@ -41,7 +41,7 @@
       beta: This field reuse is beta and subject to change.
       otel:
         - relation: match
-    - name: tool.call.results
+    - name: tool.call.result
       type: flattened
       description: The result returned by the tool call (if any and if execution was successful).
       example: TODO