Upgrade the metadata for easier discoverability

Hello!

This pull request adds some missing metadata that makes it easier to find this model.
cc

@wxy9326


- Tom Aarsen

README.md

@@ -1,3 +1,8 @@
 ---
 license: mit
----
+language:
+- en
+library_name: transformers
+tags:
+- sentence-transformers
+---