Mention the #ingress-nginx Slack channel

[foxylion]

There is a dedicated channel for ingress nginx, mention this in the README.

[codecov-io]

Codecov Report

Merging #2531 into master will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2531      +/-   ##
==========================================
+ Coverage   41.55%   41.57%   +0.01%     
==========================================
  Files          74       74              
  Lines        5270     5270              
==========================================
+ Hits         2190     2191       +1     
+ Misses       2784     2782       -2     
- Partials      296      297       +1

Impacted Files	Coverage Δ
internal/watch/file_watcher.go	84.61% <0%> (+3.84%)	⬆️

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[aledbf]

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, foxylion

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