Description extension not working if dot in username

https://github.com/adobe/jsonschema2md/blob/2a0f6f8e9f0d3454dc330ba9eb2fef7ebdf50875/lib/formatInfo.js#L67

If your user has a dot in it like `j.doe` then it will cut it off at `j` and looks for the path with `j.description.md` at the end and fails with `Error: ENOENT: no such file or directory, open '/Users/j.description.md'`.

This way the descriptions extension are not imported.

Start at lib/formatInfo.js around line 67 and reproduce the failure with a username such as j.doe. Trace how the username is used to locate the description file; done means the full dotted username is preserved and the description extension imports without the ENOENT path error.

Written by the indexing model from the issue text.