Update Readme.md. Fix commas. (#479)

Readme.md

@@ -310,12 +310,12 @@ Additionally, `customPrettifiers` can be used to format the `time`, `hostname`,
     // The argument for the level-prettifier may vary depending
     // on if the levelKey option is used or not.
     // By default this will be the same numerics as the Pino default:
-    level: logLevel => `LEVEL: ${logLevel}`
+    level: logLevel => `LEVEL: ${logLevel}`,
 
     // other prettifiers can be used for the other keys if needed, for example
-    hostname: hostname => colorGreen(hostname)
-    pid: pid => colorRed(pid)
-    name: name => colorBlue(name)
+    hostname: hostname => colorGreen(hostname),
+    pid: pid => colorRed(pid),
+    name: name => colorBlue(name),
     caller: caller => colorCyan(caller)
   }
 }