fix: typo in English fieldname

package.json

src/templates/vocabulary/.template-spec.yaml

src/templates/vocabulary/hear/front.html

src/templates/vocabulary/read_hanzi/back.html

src/templates/vocabulary/read_hanzi_traditional/back.html

src/templates/vocabulary/read_pinyin/back.html

src/templates/vocabulary/speak/back.html

src/templates/vocabulary/write/back.html

src/templates/vocabulary/write_traditional/back.html