Update if/else content in JavaScript roadmap (#2162)

Add syntax highlighting in code snippet.

content/roadmaps/106-javascript/content/107-javascript-control-flow/101-conditional-statements/100-if-else.md

@@ -2,7 +2,8 @@
 
 The `if` statement executes a statement if a specified condition is `truthy`. If the condition is `falsy`, another statement in the optional `else` clause will be executed.
 
-```
+## Example
+```js
 if (condition) {
   statement1
 } else {
@@ -11,5 +12,5 @@ if (condition) {
 ```
 
 <ResourceGroupTitle>Free Content</ResourceGroupTitle>
-<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else'>if...else</BadgeLink>
-<BadgeLink colorScheme='yellow' badgeText='Read' href='https://javascript.info/ifelse'>Conditional branching: if, '?'</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else'>if...else - MDN docs</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://javascript.info/ifelse'>Conditional branching: if, '?' - javascript.info</BadgeLink>