Add license and pipeline tag

This PR adds the `feature-extraction` pipeline tag to the model card, ensuring the model is findable at https://huggingface.co/models?pipeline_tag=feature-extraction. It also adds the Apache 2.0 license, as specified in the Github repository.

README.md

@@ -1,11 +1,13 @@
 ---
-library_name: transformers
+base_model:
+- google-bert/bert-base-uncased
 datasets:
 - microsoft/ms_marco
 language:
 - en
-base_model:
-- google-bert/bert-base-uncased
+library_name: transformers
+license: apache-2.0
+pipeline_tag: feature-extraction
 ---
 
 # Model Card