Create generation_config.json

fix: Entry Not Found for url: https://huggingface.co/openchat/openchat_3.5/resolve/main/generation_config.json.
of many projects require generation_config.json
when using
```
model.generation_config = GenerationConfig.from_pretrained("openchat/openchat_3.5")
```

added more fields with imone's suggest!

generation_config.json

@@ -0,0 +1,9 @@
+{
+  "_from_model_config": true,
+  "bos_token_id": 1,
+  "eos_token_id": 32000,
+  "max_length": 8192,
+  "pad_token_id": 0,
+  "temperature": 0.5,
+  "transformers_version": "4.34.1"
+}