Add rinkeby network and extend some logs/docs

scripts/upgrade-example.js

@@ -9,6 +9,9 @@ async function main() {
   const ContributorV2 = await ethers.getContractFactory("Contributor");
   const contributor = await upgrades.upgradeProxy(kredits.Contributor.address, ContributorV2);
   console.log("Contributor upgraded");
+  console.log(`Contirbutor address: ${contributor.address}`);
+
+  await contributor.deployTransaction.wait();
 
   console.log("DONE!");
 }