fix context sentences in YAML to ensure vocab emphasis

docs/howtostudykorean/theme/03-eating.md

@@ -866,9 +866,9 @@ vocabulary:
     - ko: 김밥
       en: A roll of rice and other ingredients wrapped in seaweed
       examples:
-        - ko: 김밥 1줄 주세요
+        - ko: "**김밥** 1줄 주세요"
           en: One (line) of **kimbab** please
-        - ko: 김밥은 얼마예요?
+        - ko: "**김밥**은 얼마예요?"
           en: How much is (the) **kimbab**?
 
     - ko: 떡