modify hardhat readme & upgrade hardhat version

Author: dalaocu

basic/07-hardhat/README.md

@@ -57,7 +57,9 @@ module.exports = {
     // rinkeby 测试网络
     rinkeby: {
       // 请将 INFURA_ID 替换成你自己的
-      url: 'https://rinkeby.infura.io/v3/{INFURA_ID}',
+      // url: 'https://rinkeby.infura.io/v3/{INFURA_ID}',
+      url: 'https://rinkeby.infura.io/v3/' + process.env.INFURA_ID, //<---- 在.env文件中配置自己的INFURA_ID
+
       // 填写测试账户的私钥，可填写多个
       accounts: [privateKey1, privateKey2, ...]
     }

basic/07-hardhat/hardhat.config.js

@@ -30,23 +30,23 @@ module.exports = {
       */
     },
     rinkeby: {
-      url: 'https://rinkeby.infura.io/v3/' + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
+      url: 'https://rinkeby.infura.io/v3/' + process.env.INFURA_ID, //<---- CONFIG YOUR INFURA ID IN .ENV! (or it won't work)
       accounts: [mnemonic()],
     },
     kovan: {
-      url: 'https://kovan.infura.io/v3/' + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
+      url: 'https://kovan.infura.io/v3/' + process.env.INFURA_ID, //<---- CONFIG YOUR INFURA ID IN .ENV! (or it won't work)
       accounts: [mnemonic()],
     },
     mainnet: {
-      url: 'https://mainnet.infura.io/v3/' + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
+      url: 'https://mainnet.infura.io/v3/' + process.env.INFURA_ID, //<---- CONFIG YOUR INFURA ID IN .ENV! (or it won't work)
       accounts: [mnemonic()],
     },
     ropsten: {
-      url: 'https://ropsten.infura.io/v3/' + process.env.INFURA_ID, //<---- YOUR INFURA ID! (or it won't work)
+      url: 'https://ropsten.infura.io/v3/' + process.env.INFURA_ID, //<---- CONFIG YOUR INFURA ID IN .ENV! (or it won't work)
       accounts: [mnemonic()],
     },
     matic: {
-      url: 'https://polygon-mainnet.infura.io/v3/' + process.env.PROJECT_ID,
+      url: 'https://polygon-mainnet.infura.io/v3/' + process.env.PROJECT_ID, //<---- CONFIG YOUR INFURA ID IN .ENV! (or it won't work)
       accounts: [mnemonic()]
     },
   },

basic/07-hardhat/package.json

@@ -16,7 +16,7 @@
     "dotenv": "^10.0.0",
     "ethereum-waffle": "^3.4.0",
     "ethers": "^5.4.7",
-    "hardhat": "^2.6.4",
+    "hardhat": "^2.9.0",
     "sol-merger": "^3.1.0"
   },
   "dependencies": {