fix config option names

Author: orsinium

docs/config.md

@@ -21,7 +21,7 @@ ignore = []
 # --ignore-categories: categories of mypy errors to ignore, e.g. "note" or "call-arg"
 ignore_categories = []
 # --sort-baseline: sort the baseline file
-sort-baseline = false
+sort_baseline = false
 # --default-branch: default git branch name
-default-branch = ''
+default_branch = ''
 ```