doc: fix multiline return comments in querystring

Changes the multiline return example commments in querystring
which have the example out-of-comment, into single comment
lines to remain consistent with other docs.

PR-URL: #5705
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

doc/api/querystring.markdown

@@ -28,15 +28,13 @@ Example:
 
 ```js
 querystring.parse('foo=bar&baz=qux&baz=quux&corge')
-// returns
-{ foo: 'bar', baz: ['qux', 'quux'], corge: '' }
+// returns { foo: 'bar', baz: ['qux', 'quux'], corge: '' }
 
 // Suppose gbkDecodeURIComponent function already exists,
 // it can decode `gbk` encoding string
 querystring.parse('w=%D6%D0%CE%C4&foo=bar', null, null,
   { decodeURIComponent: gbkDecodeURIComponent })
-// returns
-{ w: '中文', foo: 'bar' }
+// returns { w: '中文', foo: 'bar' }
 ```
 
 ## querystring.stringify(obj[, sep][, eq][, options])
@@ -52,19 +50,16 @@ Example:
 
 ```js
 querystring.stringify({ foo: 'bar', baz: ['qux', 'quux'], corge: '' })
-// returns
-'foo=bar&baz=qux&baz=quux&corge='
+// returns 'foo=bar&baz=qux&baz=quux&corge='
 
 querystring.stringify({foo: 'bar', baz: 'qux'}, ';', ':')
-// returns
-'foo:bar;baz:qux'
+// returns 'foo:bar;baz:qux'
 
 // Suppose gbkEncodeURIComponent function already exists,
 // it can encode string with `gbk` encoding
 querystring.stringify({ w: '中文', foo: 'bar' }, null, null,
   { encodeURIComponent: gbkEncodeURIComponent })
-// returns
-'w=%D6%D0%CE%C4&foo=bar'
+// returns 'w=%D6%D0%CE%C4&foo=bar'
 ```
 
 ## querystring.unescape