Update 6-knowledge-check.yml

Author: QijieXue

learn-pr/wwl-language/csharp-write-first/6-knowledge-check.yml

@@ -14,7 +14,7 @@ durationInMinutes: 3
 quiz:
   title: "Check your knowledge"
   questions:
-  - content: "What is the primary job of the compiler?"
+  - content: "What is the primary job of the compiler?" 
     choices:
     - content: "The compiler primarily locates spelling mistakes in your code."
       isCorrect: false
@@ -46,4 +46,4 @@ quiz:
       explanation: "Correct! The semi-colon must be used at the end of a code statement."
     - content: "The string should use single-quotes."
       isCorrect: false
-      explanation: "Incorrect. A string literal must be surrounded in double-quotes.  A char literal is surrounded in single quotes."
+      explanation: "Incorrect. A string literal must be surrounded in double-quotes.  A char literal is surrounded in single quotes."