set correct base_model

So it's listed when you browse from the model tree section on https://huggingface.co/mattshumer/Reflection-Llama-3.1-70B (https://huggingface.co/models?other=base_model:quantized:mattshumer/Reflection-Llama-3.1-70B)

README.md

@@ -1,5 +1,5 @@
 ---
-base_model: meta-llama/Meta-Llama-3.1-70B-Instruct
+base_model: mattshumer/Reflection-Llama-3.1-70B
 license: llama3.1
 pipeline_tag: text-generation
 tags: