Improve Alternate*Authority docs. Bug 6387.

  o Documentation:

    - Clarify the documentation for the Alternate*Authority options.

      Fixes bug 6387.

**AlternateHSAuthority** [__nickname__] [**flags**] __address__:__port__ __fingerprint__ +

**AlternateBridgeAuthority** [__nickname__] [**flags**] __address__:__port__ __ fingerprint__::

    As DirServer, but replaces less of the default directory authorities. Using

    These options behave as DirServer, but they replace fewer of the

    default directory authorities. Using

    AlternateDirAuthority replaces the default Tor directory authorities, but

    leaves the hidden service authorities and bridge authorities in place.

    Similarly, Using AlternateHSAuthority replaces the default hidden service

    authorities, but not the directory or bridge authorities.

    leaves the default hidden service authorities and bridge authorities in

    place.  Similarly, AlternateHSAuthority replaces the default hidden

    service authorities, but not the directory or bridge authorities; and

    AlternateBridgeAuthority replaces the default bridge authority,

    but leaves the directory and hidden service authorities alone.

**DisableAllSwap** **0**|**1**::

    If set to 1, Tor will attempt to lock all current and future memory pages,