[DOC] Update pattern matching docs for 3.2

* Remove section about experimental status
* Add references to core objects that can deconstruct

doc/syntax/pattern_matching.rdoc

@@ -415,6 +415,11 @@ Additionally, when matching custom classes, the expected class can be specified
   end
   #=> "matched: 1"
 
+These core and library classes implement deconstruction:
+
+* MatchData#deconstruct and MatchData#deconstruct_keys;
+* Time#deconstruct_keys, Date#deconstruct_keys, DateTime#deconstruct_keys.
+
 == Guard clauses
 
 +if+ can be used to attach an additional condition (guard clause) when the pattern matches. This condition may use bound variables:
@@ -445,29 +450,6 @@ Additionally, when matching custom classes, the expected class can be specified
   end
   #=> "matched"
 
-== Current feature status
-
-As of Ruby 3.1, find patterns are considered _experimental_: its syntax can change in the future. Every time you use these features in code, a warning will be printed:
-
-  [0] => [*, 0, *]
-  # warning: Find pattern is experimental, and the behavior may change in future versions of Ruby!
-  # warning: One-line pattern matching is experimental, and the behavior may change in future versions of Ruby!
-
-To suppress this warning, one may use the Warning::[]= method:
-
-  Warning[:experimental] = false
-  eval('[0] => [*, 0, *]')
-  # ...no warning printed...
-
-Note that pattern-matching warnings are raised at compile time, so this will not suppress the warning:
-
-  Warning[:experimental] = false # At the time this line is evaluated, the parsing happened and warning emitted
-  [0] => [*, 0, *]
-
-So, only subsequently loaded files or `eval`-ed code is affected by switching the flag.
-
-Alternatively, the command line option <code>-W:no-experimental</code> can be used to turn off "experimental" feature warnings.
-
 == Appendix A. Pattern syntax
 
 Approximate syntax is: