[Docs] Standardize deprecated rule notice

[bmish]

❌ This rule is deprecated.

• Standardize deprecation notice in rule docs to be more consistent with the other rule notices and add a test that it's present for deprecated rules. Note that rule-specific deprecation information is allowed at the end of the line for this notice.
• In the README rules list, mention if a rule is deprecated next to its description. Note that I chose not to add a deprecation column like the other columns we have for recommended/fixable/suggestable because I didn't want to waste more horizontal width on this for something that is probably rare. We can always switch to a separate column in the future if needed.

Extracted from this PR: #3362

[codecov]

Codecov Report

Merging #3364 (885afc3) into master (13d23b8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3364   +/-   ##
=======================================
  Coverage   97.54%   97.54%           
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  Files         123      123           
  Lines        8873     8873           
  Branches     3244     3244           
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  Hits         8655     8655           
  Misses        218      218           

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