Add pipeline tag and library name

This PR adds the `pipeline_tag` and `library_name` to the model card metadata. This ensures the model can be found at https://huggingface.co/models?pipeline_tag=text-to-speech and the proper library is recognized for the model.

README.md

@@ -1,5 +1,7 @@
 ---
 license: cc-by-nc-4.0
+pipeline_tag: text-to-speech
+library_name: transformers
 ---
 
 # CapSpeech