Add mempool-config.json to .gitignore, update sample, update README

backend/.gitignore

@@ -1,5 +1,8 @@
 # See http://help.github.com/ignore-files/ for more about ignoring files.
 
+# production config
+mempool-config.json
+
 # compiled output
 /dist
 /tmp

backend/mempool-config.sample.json

@@ -1,10 +1,10 @@
 {
   "ENV": "dev",
   "DB_HOST": "localhost",
-  "DB_PORT": 8889,
-  "DB_USER": "",
-  "DB_PASSWORD": "",
-  "DB_DATABASE": "",
+  "DB_PORT": 3306,
+  "DB_USER": "mempool",
+  "DB_PASSWORD": "mempool",
+  "DB_DATABASE": "mempool",
   "HTTP_PORT": 3000,
   "API_ENDPOINT": "/api/v1/",
   "CHAT_SSL_ENABLED": false,
@@ -16,8 +16,8 @@
   "DEFAULT_PROJECTED_BLOCKS_AMOUNT": 3,
   "KEEP_BLOCK_AMOUNT": 24,
   "BITCOIN_NODE_HOST": "localhost",
-  "BITCOIN_NODE_PORT": 18332,
+  "BITCOIN_NODE_PORT": 8332,
   "BITCOIN_NODE_USER": "",
   "BITCOIN_NODE_PASS": "",
   "TX_PER_SECOND_SPAN_SECONDS": 150
-}
+}