docs: add deprecation warning

6 jobs for master in 60 minutes and 33 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Test
passed test-macos #627307
macos_highsierra

00:17:05

 
  Build
passed build-latest #627308

00:42:22

passed build-nightly #627309

00:32:11

 
  Docs
passed docs #627310

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  Deploy
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passed pages:deploy

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