Removes documentation about restricting access to /admin

[joesiltberg]

Fixes #2937

[codecov]

Codecov Report

Merging #2946 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2946   +/-   ##
=======================================
  Coverage   82.86%   82.86%           
=======================================
  Files         242      242           
  Lines       15222    15222           
  Branches     2830     2830           
=======================================
  Hits        12614    12614           
  Misses       1700     1700           
  Partials      908      908           

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[dracos]

Thanks!