adds documentation for sniff WordPress.PHP.DiscouragedPHPFunctions

[tikifez]

Related to #1722

[rodrigoprimo]

Thanks for your contribution, @tikifez! Before I review this PR in detail, could you please fix the same points, where applicable, that were discussed in #2487?

Quickly skimming through the XML file, I can see some issues with indentation, lack of <em> tags, and no newline at the end of the file.

[rodrigoprimo]

@tikifez, I was just wondering if you'll have a chance to finish this off in the near future. It would be great if this PR could be included in the next WPCS release.

If you haven't got time or lost interest, please let us know and we'll see if we can find someone to take over. Thanks!

[tikifez]

@tikifez, I was just wondering if you'll have a chance to finish this off in the near future. It would be great if this PR could be included in the next WPCS release.

If you haven't got time or lost interest, please let us know and we'll see if we can find someone to take over. Thanks!

I'll get it done this week! Thanks!

[rodrigoprimo]

@tikifez, please let us know within a week if you are still interested in finishing this PR. If we don't hear back from you, we will presume you don't have time, and we will see if we can find someone else to take over and finish it. Thanks for your work so far!