update slack message about new users so it contains more info (user's full name, email) and a emoji
update slack message about new users so it contains more info (user's full name, email) and a emoji

tndatacommons/tndata_backend,tndatacommons/tndata_backend,tndatacommons/tndata_backend,izzyalonso/tndata_backend,izzyalonso/tndata_backend,izzyalonso/tndata_backend,tndatacommons/tndata_backend,izzyalonso/tndata_backend