Minor typo in readme.md

[NPalopoli]

Corrected sentence that should end in '.' instead of '?'

[bressler95tops]

Thank you @NPalopoli, I will add this (and your other pull requests) to our review process. I expect initial review to occur at the end of this month and monthly thereafter. Stay tuned, as we get to your contribution. We greatly appreciate it and feel free to continue submitting suggestions.