Minor typos

[whwang299]

Hi. Thanks for sharing a nice work.

There seem to be some minor typos in the docstrings.

https://github.com/microsoft/genalog/blob/b8b9fbabdde5855e8bcc9db025e78cc619e15cd1/genalog/text/alignment.py#L203-L207

Maybe it should be changed as below? '.' is for substition → '.' is for substitution '-' indicates gap → ' ' indicates gap

Thanks.

[laserprec]

Thanks for bringing that up 😄. Will address it in the next release.