Use consistent capitalization of "authd"

[adombeck]

We have been consistently using "authd" in all lowercase in the documentation since 6c4355f.

Let's use it consistently everywhere.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.67%. Comparing base (6ff09d2) to head (db2dda4).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1169      +/-   ##
==========================================
+ Coverage   87.64%   87.67%   +0.03%     
==========================================
  Files          90       90              
  Lines        6222     6222              
  Branches      111      111              
==========================================
+ Hits         5453     5455       +2     
+ Misses        713      711       -2     
  Partials       56       56              

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