[DOC] Combine docs for Method#call aliases

RDoc does not parse the documentation for the Method#call aliases, so we
should combine the aliases into one documentation.

Author: peterzhu2118

proc.c

@@ -2642,13 +2642,20 @@ method_dup(VALUE self)
     return clone;
 }
 
-/*  Document-method: Method#===
- *
+/*
  *  call-seq:
- *     method === obj   -> result_of_method
+ *     meth.call(args, ...) -> obj
+ *     meth[args, ...] -> obj
+ *     method === obj -> result_of_method
+ *
+ *  Invokes the <i>meth</i> with the specified arguments, returning the
+ *  method's return value.
  *
- *  Invokes the method with +obj+ as the parameter like #call.
- *  This allows a method object to be the target of a +when+ clause
+ *     m = 12.method("+")
+ *     m.call(3)    #=> 15
+ *     m.call(20)   #=> 32
+ *
+ *  Using Method#=== allows a method object to be the target of a +when+ clause
  *  in a case statement.
  *
  *      require 'prime'
@@ -2659,32 +2666,6 @@ method_dup(VALUE self)
  *      end
  */
 
-
-/*  Document-method: Method#[]
- *
- *  call-seq:
- *     meth[args, ...]         -> obj
- *
- *  Invokes the <i>meth</i> with the specified arguments, returning the
- *  method's return value, like #call.
- *
- *     m = 12.method("+")
- *     m[3]         #=> 15
- *     m[20]        #=> 32
- */
-
-/*
- *  call-seq:
- *     meth.call(args, ...)    -> obj
- *
- *  Invokes the <i>meth</i> with the specified arguments, returning the
- *  method's return value.
- *
- *     m = 12.method("+")
- *     m.call(3)    #=> 15
- *     m.call(20)   #=> 32
- */
-
 static VALUE
 rb_method_call_pass_called_kw(int argc, const VALUE *argv, VALUE method)
 {