Bug: README document contained a custom log example but imports were incorrect plus unused import

[Coderrob]

Describe the bug
Reading through the README documentation I was looking at custom logging examples. I noticed the import was from a 'base' logger but the imported types came from tslog. Looked like a copy paste problem so opened a PR to make corrections in case anyone copy pasted to start a custom logger.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://github.com/fullstack-build/tslog/blob/master/README.md?plain=1#L243
2. See unused import and looks like from 'tslog'

Expected behavior
Updated documentation.

Screenshots