Add karsha.biz to merchants.yml

Fix #431

_data/merchants.yml

@@ -20,6 +20,8 @@
       url: https://www.cryptopia.co.nz/Exchange?market=XMR_BTC
     - name: Kaiserex
       url: https://www.kaiserex.com/
+    - name: Karsha
+      url: https://karsha.biz/
     - name: Kraken (XMRUSD, XMREUR, XMRBTC)
       url: https://www.kraken.com/
     - name: Liberalcoins