Added note to HOWTO suggesting users to move to electrumx as electrum-server is no longer maintained.
Added note to HOWTO suggesting users to move to electrumx as electrum-server is no longer maintained.

spesmilo/electrum-server,shsmith/electrum-server,GroestlCoin/electrum-grs-server,shsmith/electrum-server,GroestlCoin/electrum-grs-server,Verbalist/electrum-server,pooler/electrum-ltc-server,spesmilo/electrum-server,pooler/electrum-ltc-server,Verbalist/electrum-server