Add sample config and update gitignore

.gitignore

@@ -23,3 +23,4 @@ yarn-debug.log*
 yarn-error.log*
 
 .eslintcache
+src/config.js

src/sample.config.js

@@ -0,0 +1,3 @@
+const WS_BASE = "http://localhost:5050/";
+
+export { WS_BASE };