Rename ups-protocols to protocols and fixe references

[aquette]

As in many other places, the UPS mention is extraneous and not true, since we also have PDU and ATS at least.

So rename the ups-protocols page and mentions to simply "protocols".
This is spread across several repositories:

• nut
  ** docs/documentation.txt:- link:ups-protocols.html[UPS protocols library]
  ** docs/documentation.txt:- link:ups-protocols.html[UPS protocols library]
  ** docs/acknowledgements.txt:link:ups-protocols.html[extensive information] on its USB/HID devices, along
  ** docs/acknowledgements.txt:provided link:ups-protocols.html[all protocols information]. Elio Parisi has
  ** drivers/blazer.c: * found online at http://www.networkupstools.org/ups-protocols/megatec.html
  ** drivers/riello_usb.c: * http://www.networkupstools.org/ups-protocols/riello/PSGPSER-0104.pdf
  ** drivers/riello.h: * http://www.networkupstools.org/ups-protocols/riello/PSGPSER-0104.pdf
  ** drivers/riello.h: * http://www.networkupstools.org/ups-protocols/riello/PSSENTR-0100.pdf
  ** drivers/riello_ser.c: * found online at "http://www.networkupstools.org/ups-protocols/riello/PSGPSER-0104.pdf"
  ** drivers/riello_ser.c: * and "http://www.networkupstools.org/ups-protocols/riello/PSSENTR-0100.pdf".
  ** drivers/delta_ups-mib.c: * MIB reference: http://www.networkupstools.org/ups-protocols/snmp/DeltaUPSv4.mib
  ** drivers/riello.c: * http://www.networkupstools.org/ups-protocols/riello/PSGPSER-0104.pdf
  ** drivers/riello.c: * http://www.networkupstools.org/ups-protocols/riello/PSSENTR-0100.pdf
  ** NEWS: http://www.networkupstools.org/ups-protocols.html#_riello
• nut-website
  ** Makefile.am: ups-protocols.html
  ** rename ups-protocols.txt to protocols.txt