feat: update DEMO site. add "use my img" for demo site

feat: upload img demo

fix: demo page

chore: Update package version

doc: update README

fix: add className props

fix: add comments to props of Mockups

doc: update README

Merge pull request #4 from jung-youngmin/develop

doc: update README

feat: add download to png on Demo page

fix: change default screen color to "transparent"

Merge pull request #3 from jung-youngmin/develop

fix: Change multiple files into one file

fix: fix typo error : navBarcolor -> navBarColor. Remove props memorizing