add support for justify-content

[Chaho12]

Hi, I noticed that align items is meant for vertical align and it would be great if we can set horizontal align css style using justify content option.

I tested and if you don't mind, I'll make a PR for this change
Document would be as below and UI would be

param	type	description	required	default
alignItems	String	Same with flex. Control the content of a cell	No	center
justifyContent	String	Defines how the browser distributes space between and around content items.	No	center

before

after (set age : justify-content left)

[Chaho12]

[Chaho12]

also if you don't mind, I would like to add 'ko' version option names

[waningflow]

It's OK. BTW, it's more probably spelled as 'kr' instead of 'ko'.