Minor improvements to documentation

[TWiedemann]

• Directories were referred to as "Directory() objects" at some places and as "IsDirectory objects" at others. I changed all occurrences of the former to the latter.
• <Ref Chap="AutoDoc"/> is actually a function, not a chapter.
• Some information about the order in which files are scanned.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.03%. Comparing base (98692f4) to head (7d5deb4).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #382   +/-   ##
=======================================
  Coverage   93.03%   93.03%           
=======================================
  Files          15       15           
  Lines        3131     3131           
=======================================
  Hits         2913     2913           
  Misses        218      218           

Files with missing lines	Coverage Δ
gap/Magic.gd	100.00% <ø> (ø)

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