MNEMONIC-261: Add mnemonic-spark info to README
MNEMONIC-261: Add mnemonic-spark info to README

NonVolatileComputing/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,yzz127/incubator-mnemonic,johnugeorge/incubator-mnemonic,yzz127/incubator-mnemonic,johnugeorge/incubator-mnemonic,paleyss/incubator-mnemonic,paleyss/incubator-mnemonic,lql5083psu/incubator-mnemonic,johnugeorge/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,lql5083psu/incubator-mnemonic,yzz127/incubator-mnemonic,lql5083psu/incubator-mnemonic,lql5083psu/incubator-mnemonic,yzz127/incubator-mnemonic,paleyss/incubator-mnemonic,NonVolatileComputing/incubator-mnemonic,paleyss/incubator-mnemonic,johnugeorge/incubator-mnemonic