Add note about changing aria-labelledby and header id
Add note about changing aria-labelledby and header id

Closes #19.

joerodrig3/css-modal,drublic/css-modal,shawinder/css-modal,ableco/css-modal,shawinder/css-modal,0111001101111010/css-modal,joerodrig3/css-modal,ableco/css-modal,drublic/css-modal