Fix rendering of docs

[JCGoran]

This should take care of the rendering of the docs, which was caused by a combination of two things:

1. the (now deleted) line was overriding /index.html file, and was redirecting it to /html/index.html instead
2. where does the /html/index.html file come from? I believe the answer is this line here:
   

   nmodl/.github/workflows/nmodl-doc.yml

   Line 82 in 3754a71

   clean: false # Automatically remove deleted files from the deploy branch

At some point I guess the docs were (and still are) under /html/[file] instead of just /[file].

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.54%. Comparing base (3754a71) to head (7e9b3f0).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1302   +/-   ##
=======================================
  Coverage   85.54%   85.54%           
=======================================
  Files         178      178           
  Lines       13415    13415           
=======================================
  Hits        11476    11476           
  Misses       1939     1939           

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[bbpbuildbot]

Logfiles from GitLab pipeline #215374 (:white_check_mark:) have been uploaded here!

Status and direct links:

• ✅ spack_setup
• ✅ build:intel
• ✅ build:nvhpc
• ✅ test:intel
• ✅ test:nvhpc