Adapt cffinit note when user updates file

[sdruskat]

Idea

When users follow the "Update" track through the application (i.e., click the button and paste), the note in the header comment in the generated string could reflect this, i.e.:

# This CITATION.cff file was updated with cffinit.             <--- "updated" replacing "generated"
# Visit https://bit.ly/cffinit to generate yours today!

Rationale

When analyzing use of cffinit, the string can be used to estimate use of the update feature. This would have the same caveats of course as using the header to identify cffinit use in general: users could remove it, change it, or add it manually which would skew results.