document localization template interpolation, like ${0} #1404

// templates has key with the template:
  check_email: html`checking ${ 0 }`, 
  ...
  check_email_does_not_work: (args)=>html`checking ${ args.address }`
// unclear how to make the above templates work, except for the index approach 0, 1... 
// and whether this is the only option available for logic in templates


const address = `user@host`; 
msg(str`checking...${address}`, {id:'check_email'})

// like
greeting: html`<b>Hola Mundo</b>`,
parameterized: html`<b>Hola ${0}</b>`,
htmlOrderChange: html`<b>2:${1} 1:${0}</b>`,