docs: use npm install in README

Author: afc163

README.md

@@ -63,7 +63,7 @@ export default ({ target }: { target: HTMLDivElement | null }) => {
 Run the local dumi site:
 
 ```bash
-ut install
+npm install
 npm start
 ```
 
@@ -90,7 +90,7 @@ The hook observes the provided target element or element array with the same cal
 ## Development
 
 ```bash
-ut install
+npm install
 npm start
 npm test
 npm run tsc

README.zh-CN.md

@@ -63,7 +63,7 @@ export default ({ target }: { target: HTMLDivElement | null }) => {
 运行本地 dumi 站点：
 
 ```bash
-ut install
+npm install
 npm start
 ```
 
@@ -90,7 +90,7 @@ useMutateObserver(target, callback, options);
 ## 本地开发
 
 ```bash
-ut install
+npm install
 npm start
 npm test
 npm run tsc