Fix md formatting issues

Author: CristinaSolana

manual/en-US/coding-standards/chapters/javascript.md

@@ -90,7 +90,7 @@ for ( prop in object ) {
 
 #### Exceptions
 
-** First or only argument is an object, array or callback function.**
+**First or only argument is an object, array or callback function.**
 
 **No space before the first argument:**
 
@@ -109,8 +109,6 @@ foo(function() {
 
 **Function with a callback, object, or array as the last argument:**
 
-```
-
 **No space after the last argument:**
 
 ```
@@ -214,7 +212,7 @@ var baz = 'qux';
 
 ```
 var foo = 'bar',
-    bar = 'baz',
+	bar = 'baz',
     baz = 'qux';
 ```
 
@@ -420,7 +418,10 @@ if ( test ) {
 - Place above the code it refers to.
 - A space between double forward slashes and comment text.
 
-`// I am a single line comment.`
+```
+// I am a single line comment.
+```
+
 
 **Multiline**
 
@@ -447,4 +448,4 @@ if ( test ) {
 **With help from:**
 
 - [jQuery JS Style Guide](https://contribute.jquery.org/style-guide/js)
-- [Idiomatic JS](https://github.com/rwaldron/idiomatic.js)
+- [Idiomatic JS](https://github.com/rwaldron/idiomatic.js)