MONGOID-5266 Deprecate JRuby support (#5187)

Co-authored-by: Oleg Pudeyev <code@olegp.name>

Author: p-mongo

docs/reference/compatibility.txt

@@ -105,7 +105,7 @@ is deprecated.
      -
      -
      -
-     - |checkmark|
+     - D
 
    * - 7.3
      - |checkmark| [#mongoid-7.3-ruby-3.0]_

docs/release-notes/mongoid-7.4.txt

@@ -28,6 +28,9 @@ Ruby Version Support
 As of version 7.4, Mongoid supports Ruby 2.5+.
 Support for Ruby 2.4 and earlier has been dropped.
 
+As of Mongoid 7.4, JRuby support is deprecated. Mongoid 8 will not support
+JRuby.
+
 
 Support for MongoDB 3.4 and Earlier Servers Deprecated
 ------------------------------------------------------