[mintnet-kubernetes] use `tr -d` as per Frey suggestion

mintnet-kubernetes/examples/basecoin/README.md

@@ -25,13 +25,13 @@ make create
 3. get account's address of the second pod
 
    ```
-   kubectl exec -c app tm-1 -- cat /app/key.json | grep "address"
+   ADDR=`kubectl exec -c app tm-1 -- cat /app/key.json | grep "address" | tr -d "\""`
    ```
 
 4. send 5 coins to it from the first pod
 
    ```
-   kubectl exec -c app tm-0 -- basecoin tx send --to 0x<address> --amount 5
+   kubectl exec -c app tm-0 -- basecoin tx send --to "0x$ADDR" --amount 5
    ```