Extend docs and example about wildcard TLS secret

[pleshakov]

Proposed changes

Extend docs and the example about wildcard TLS secret

[codecov-commenter]

Codecov Report

Merging #2288 (8500ad7) into master (e5bf0a7) will increase coverage by 0.02%.
The diff coverage is n/a.

❗ Current head 8500ad7 differs from pull request most recent head 8573b1c. Consider uploading reports for the commit 8573b1c to get more accurate results

@@            Coverage Diff             @@
##           master    #2288      +/-   ##
==========================================
+ Coverage   53.65%   53.68%   +0.02%     
==========================================
  Files          48       48              
  Lines       14199    14199              
==========================================
+ Hits         7619     7623       +4     
+ Misses       6340     6338       -2     
+ Partials      240      238       -2     

Impacted Files	Coverage Δ
cmd/nginx-ingress/main.go	6.31% <ø> (ø)
internal/k8s/configuration.go	95.85% <0.00%> (+0.38%)	⬆️

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