chore: copy README to docfx-yml dir (#969)

* chore: copy README to docfx-yml dir

- also cleaning up uneccessary dash in destination_prefix

* chore: update path

synthtool/gcp/templates/java_library/.kokoro/release/publish_javadoc11.sh

@@ -40,6 +40,9 @@ export VERSION=$(grep ${NAME}: versions.txt | cut -d: -f3)
 # generate yml
 mvn clean site -B -q -P docFX
 
+# copy README to docfx-yml dir and rename index.md
+cp README.md target/docfx-yml/index.md
+
 pushd target/docfx-yml
 
 # create metadata
@@ -52,4 +55,4 @@ python3 -m docuploader create-metadata \
 python3 -m docuploader upload . \
  --credentials ${CREDENTIALS} \
  --staging-bucket ${STAGING_BUCKET_V2} \
- --destination-prefix docfx-
+ --destination-prefix docfx