Clarification of adding years to copyright notices

[Richard M. Stallman]

We've clarified one paragraph to answer the uncertainties that
were expressed here a few days ago.


To update the list of year numbers, add each year in which you have
made nontrivial changes to the package.  (Here we assume you're using
a publicly accessible revision control server, so that every revision
installed is also immediately and automatically published.)  Several
trivial changes that add up to a nontrivial change do count as such.
When you add the new year, you should add it in the copyright notice
of each file of the package.