This is a small extension to a standard "Textbox" editor, that allows you to specify a prefix and/or suffix string to show alongside the editor.
Sometimes that's much better than trying to use the description to explain that you should only type in e.g. the username for an email account or similar.
This package should work in both Umbraco 7 and Umbraco 8.
On macOS you can run the build.sh script from the terminal, which will
build a ZIP file in the dist folder that is installable from
Umbraco 8's Packages section or Umbraco 7's Developer > Packages section.
The build script versions the files so it's easier to test the package inside an Umbraco installation by uninstalling the existing version and then installing a new build. Existing data-types keep their data as long as their alias and/or storage type isn't changed.
To update the version number, increment the packageVersion entity in the
src/package.ent file.