Drop the doc comment for the hidden forwarding parameter argument

`enable_forwarding_params` is a hidden argument on private entry points,
so it doesn't belong in the signature's documentation.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015bgoC4byczqmYRzNrDkVrL

Author: claude

sig/parser.rbs

@@ -136,10 +136,6 @@ module RBS
 
     def self._parse_type: (Buffer, Integer start_pos, Integer end_pos, Array[Symbol] variables, bool require_eof, bool void_allowed, bool self_allowed, bool classish_allowed) -> Types::t?
 
-    # The `enable_forwarding_params` argument enables `(...)` forwarding
-    # parameters, which are experimental and have no type checking semantics
-    # yet. It is deliberately not exposed through the public `parse_*` methods,
-    # so signatures written for the gem can't use the syntax.
     def self._parse_method_type: (Buffer, Integer start_pos, Integer end_pos, Array[Symbol] variables, bool require_eof, bool enable_forwarding_params) -> MethodType?
 
     def self._parse_signature: (Buffer, Integer start_pos, Integer end_pos, bool enable_forwarding_params) -> [Array[AST::Directives::t], Array[AST::Declarations::t]]