Bug fix: Report instances of items that used to be covered by a now missing expect entry

Report instances of items that used to be covered by a now missing expect entry

Setup

1. You have helllo in a file.log
2. You have Helllo in a README.md
3. You add helllo to expect.txt to make check-spelling happy

Action

1. You delete file.log
2. You commit
3. You push

Without this change

check-spelling would complain about Helllo (suggesting adding it to expect.txt) and suggest removing helllo from expect.txt, but it wouldn't explain where it found Helllo.

With this change

check-spelling would complain about Helllo (suggesting adding it to expect.txt), suggest removing helllo from expect.txt, and explain it found Helllo in README.md.

Availability

Expected to be available in v0.0.22