This is a good proposal and certainly the Apple I is worthy of recognition. I suggest that the words "Introduction of" be dropped from the milestone title. It is the computer itself that is the focus of the milestone.
Topic on Milestone-Proposal talk:Introduction of the Apple I Computer: 1976
I concur and would simply add that side-by-side recognition of both the Apple I and the Apple II seems most fitting in the evolving portrait of computing that IEEE Milestones over time will recognize.
The Apple I is definitely worthy of a milestone, however the current wording is not assertive of its claim. Consider wording such as "The Apple I was the first to..." or "The Apple I enabled..." or "The Apple I led to..." ---Dave Bart