Improve ForbiddenMethodCall documentation

[BraisGabin]

Now it's not a Comma separated list. It's just a list.

[codecov]

Codecov Report

Merging #4166 (39c890c) into main (954bd5e) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #4166   +/-   ##
=========================================
  Coverage     83.45%   83.45%           
  Complexity     3181     3181           
=========================================
  Files           465      465           
  Lines          9104     9104           
  Branches       1774     1774           
=========================================
  Hits           7598     7598           
  Misses          572      572           
  Partials        934      934           

Impacted Files	Coverage Δ
...turbosch/detekt/rules/style/ForbiddenMethodCall.kt	92.10% <ø> (ø)

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