Updated Plugins Guide - questions and RFT

[Alexander Belchenko]

Just a quick note: win32symlinks plugin is not maintained and I'm really don't know is it worked
with recent bzr. Also in the past I found it to fragile to use in production: while building working
tree (on initial checkout) works but merge/updating tree may break symlinks and transform them into
regular files in dirstate.

I'd better removed it from main listing, or make BIG FLASHING WARNING about it's possible brokeness.