Merge pull request #209 from PyFixate/mypy-exclude-help

an example of how to unintentionally break the mypy config

mypy.ini

@@ -17,12 +17,24 @@
 # tests are severely broken and seem to be confusing the mypy path, so don't include for now
 files = scripts,src/fixate/
 ignore_missing_imports=true
+
 # here is all the broken stuff to eventually fix up
 # this list should not be added to
 # delete entries from here as things get worked on
 # if things break in the future from turning on new rules,
 # then they should be locally disabled for the module they break
 # (or fix the actual error)
+# WARNING - this confval is not a list of files, it is actually a regex
+# as an example of what can go wrong to the ill informed see below
+# ...
+#    config/
+#    (
+#        __init__.py <- deleting this line
+#        |helper.py <- without removing the prepended | on this line
+#    )
+# ... will end up excluding all files within the config folder, rather than just helper.py
+# https://mypy.readthedocs.io/en/stable/config_file.html#confval-exclude
+# the -v flag can be used to inspect the files actually excluded
 exclude = (?x)
     (
         src/fixate/