bug#4072: 23.1.50; reftex-plug-into-AUCTeX doc-string

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

,----
| reftex-plug-into-AUCTeX is a variable defined in `reftex-vars.el'.
| Its value is t
| 
| Documentation:
| *Plug-in flags for AUCTeX interface.
| This variable is a list of 4 boolean flags.  When a flag is non-nil,
| RefTeX will
| 
|   - supply labels in new sections and environments  (flag 1)
|   - supply arguments for macros like `\label'.      (flag 2)
|   - supply arguments for macros like `\ref'.        (flag 3)
|   - supply arguments for macros like `\cite'.       (flag 4)
|   - supply arguments for macros like `\index'.      (flag 5)
| 
| You may also set the variable itself to t or nil in order to turn all
| plug-ins on or off, respectively.
`----

Should that be `a list of 5 boolean flags'?
                          ^
                          |
                          +----- Not 4

Bye,

Leo