[Docs] Fix variable name author_page_links

[petervandenabeele]

I did not test this code, but the change from href to this
author_page_links seems to have a typo ?

[codecov]

Codecov Report

Merging #4286 into master will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4286      +/-   ##
==========================================
- Coverage   83.91%   83.88%   -0.04%     
==========================================
  Files         166      166              
  Lines        9869     9869              
  Branches     1469     1469              
==========================================
- Hits         8282     8279       -3     
- Misses       1334     1335       +1     
- Partials      253      255       +2

Impacted Files	Coverage Δ
scrapy/utils/trackref.py	82.85% <0%> (-2.86%)	⬇️
scrapy/core/downloader/__init__.py	89.31% <0%> (-1.53%)	⬇️

[elacuesta]

Good catch, thanks!

[kmike]

Thanks @petervandenabeele!