Update root env example for LLM options

.env.example

@@ -18,8 +18,18 @@ RUN_MIGRATIONS=true
 PIPELINE_RETRY_LIMIT=1
 
 # LLM provider credentials for POCGraphGen.
+# Configure at least one provider.
 ANTHROPIC_API_KEY=
 OPENAI_API_KEY=
+OPENROUTER_API_KEY=
+OPENROUTER_BASE_URL=https://openrouter.ai/api/v1
+OPENROUTER_HTTP_REFERER=
+OPENROUTER_X_TITLE=
 AZURE_OPENAI_API_KEY=
 AZURE_OPENAI_ENDPOINT=
+AZURE_OPENAI_DEPLOYMENT=gpt-4o
 GOOGLE_API_KEY=
+
+# Optional LLM overrides.
+LLM_MODEL=
+LLM_MAX_TOKENS=4096