feat: connect backend with the frontend

.env.example

@@ -1,3 +1,6 @@
+# Backend environment variables #
+
+# Must be a PostgreSQL db connection string
 DATABASE_URL=postgresql://user:password@localhost:5432/mydatabase
 
 # [dev, stage, prod]
@@ -15,4 +18,7 @@ HASHIDS_SALT=default-insecure-salt
 # random.shuffle(base61)
 # print("".join(base61))
 ###
-ENCODER_ALPHABET=CnArvIseYhld2BtZipybguVKaMx4QFkcR71DTLJEP65jUGzqmw9fSoXW83HNO
+ENCODER_ALPHABET=CnArvIseYhld2BtZipybguVKaMx4QFkcR71DTLJEP65jUGzqmw9fSoXW83HNO
+
+### which origins are allowed to make cross origin requests (CORS)
+ALLOW_ORIGINS=http://localhost:3000,http://localhost:3030