docs: correct OpenRouter rerank attribution field name (xTitle -> app…

…Title)

The SDK-based OpenRouter adapters use SDKOptions, whose attribution field is
appTitle, not xTitle (xTitle only exists on the legacy raw-fetch client helper).
Fix the rerank section of the OpenRouter adapter docs and the changeset.

.changeset/openrouter-rerank.md

@@ -7,5 +7,5 @@ feat: add `openRouterRerank` / `createOpenRouterRerank` rerank adapters
 Rerank documents by relevance to a query through OpenRouter's unified
 `/v1/rerank` endpoint (e.g. `cohere/rerank-v3.5`) with the `rerank()` activity.
 Reads `OPENROUTER_API_KEY` from the environment and forwards the optional
-`httpReferer` / `xTitle` attribution headers, consistent with the other
+`httpReferer` / `appTitle` attribution headers, consistent with the other
 OpenRouter adapters.

docs/adapters/openrouter.md

@@ -272,7 +272,7 @@ console.log(rerankedDocuments[0]); // 'rainy afternoon in the city'
 
 `openRouterRerank` reads `OPENROUTER_API_KEY` from the environment; pass a key
 explicitly with `createOpenRouterRerank("cohere/rerank-v3.5", "sk-or-...")`. The
-optional `httpReferer` / `xTitle` config fields are forwarded as OpenRouter
+optional `httpReferer` / `appTitle` config fields are forwarded as OpenRouter
 attribution headers, just like the chat adapter.
 
 See the [Reranking guide](../rerank/rerank) for object documents, RAG