Correct the published metadata

Adds library_name to the model card, and pipeline_tag where it was missing.
Brings the config and card licenses into agreement, and repairs the variant
declarations that did not match the files actually published here.

README.md

@@ -1,5 +1,7 @@
 ---
-license: mit
+license: bsd-3-clause
+pipeline_tag: image-segmentation
+library_name: executorch
 ---
 
 # Introduction