Add 'summarization' tag

## Add tag: summarization
This PR adds the 'summarization' tag to the model repository.
**changes:**
- Added 'summarization' to model tags
- Updated from 4 to 5 tags
**current tags:** play,fake,region:us,test-tag
**New tags:** play,fake,region:us,test-tag,summarization
🤖This is a pull request created by the HuggingFace Hub Tagging Bot.

README.md

@@ -4,4 +4,5 @@ tags:
 - fake
 - region:us
 - test-tag
+- summarization
 ---