Update pipeline tag and specify license

This PR updates the `pipeline_tag` to `text-generation` to accurately reflect the model's text-based tabular data synthesis functionality. It also explicitly adds the MIT license to the metadata.

README.md

@@ -1,12 +1,13 @@
 ---
 library_name: transformers
+pipeline_tag: text-generation
 tags:
 - MOE
 - GPT-2
 - tabular
 - generative
 - causalLM
-pipeline_tag: tabular-regression
+license: mit
 ---
 
 # Tabby Model Card