Add single line comment in overview

Author: chenglou

docs/overview.md

@@ -18,7 +18,8 @@ Comparison                            |  `>`, `<`, `>=`, `<=`
 Boolean operations                    |  `!`, `&&`, <code>&#124;&#124;</code>
 Reference, Structural (deep) Equality |  `===`, `==`
 Immutable Lists                       |  `[1, 2, 3]`
-Immutable Prepend                     |  `[item1, item2, ...theRest]`
+Immutable List Prepend                |  `[item1, item2, ...theRest]`
 Arrays                                |  <code>[&#124;1, 2, 3&#124;]</code>
 Records                               |  `type player = {score: int}; {score: 100}`
-Comments                              |  `/* Comment here */`
+Multiline Comments                    |  `/* Comment here */`
+Single line Comments                  |  `// Comment here`