fix: formatting and clarify error message in variable declaration section

Author: nikhilrajnair

README.md

@@ -2235,19 +2235,16 @@
     | These variables do not exist in a program and are not declared                              | These variables declared in the program but have not assigned any value                |
     | If you try to read the value of an undeclared variable, then a runtime error is encountered | If you try to read the value of an undefined variable, an undefined value is returned. |
 
-        ```javascript
-
+    ```javascript
     var a;
     a; // yields undefined
 
-    b; // Throws runtime error like „Uncaught ReferenceError: b is not defined“
-
+    b; // Throws runtime error like "Uncaught ReferenceError: b is not defined"
     ```
-    This can be confusing, because it says „not defined“ instead of „not declared“ (Chrome)
+    This can be confusing, because it says `not defined` instead of `not declared` (Chrome)
 
     **[⬆ Back to Top](#table-of-contents)**
 
-    ```
 
 82. ### What are global variables