Re.c/ri's Regexp.=== documentation has an error/typo

It doesn’t put the [] character class brackets in, so the example
doesn’t work. I checked this with ri/ruby 1.6 and ri/ruby 1.8.

From ri Regexp.===:
------------------------------------------------------------- Regexp#===
rxp === aString -> true or false

···
 Case Equality---Synonym for Regexp#=~ used in case statements.
    a = "HELLO"
    case a
    when /^a-z*$/; print "Lower case\n"
    when /^A-Z*$/; print "Upper case\n"
    else;            print "Mixed case\n"
    end
 produces:
    Upper case

But:

    a = "HELLO"
    case a
    when /^a-z*$/; print "Lower case\n"
    when /^A-Z*$/; print "Upper case\n"
    else;            print "Mixed case\n"
    end
    # Added [] to regexps:
    case a
    when /^[a-z]*$/; print "Lower case\n"
    when /^[A-Z]*$/; print "Upper case\n"
    else;            print "Mixed case\n"
    end

Produces:

Mixed case
Upper case

I’ve attached a doc patch.

Cheers,
Sam