Add pipeline tag and library name

This PR ensures that the model can be found at https://huggingface.co/models?pipeline_tag=text-generation&sort=trending, and that the library is correctly recognized.

README.md

@@ -1,11 +1,13 @@
 ---
 base_model:
 - princeton-nlp/Llama-3-8B-ProLong-512k-Instruct
-license: apache-2.0
-language:
-- en
 datasets:
 - chtmp223/CLIPPER-WritingPrompts
+language:
+- en
+license: apache-2.0
+pipeline_tag: text-generation
+library_name: transformers
 ---
 
 # ProLong-512k-8B-WritingPrompts