Add upgrade instructions

README.md

@@ -31,8 +31,10 @@ Add the locale in `client/src/main.ts` and `client/gettext.config.js` and run `n
 
 ## Production
 
+### Installation
+
 Install dependencies:
-  * NodeJS (v16)
+  * NodeJS (v18)
   * MeiliSearch
 
 ```terminal
@@ -44,3 +46,13 @@ $ cp config/default.yaml config/production.yaml
 $ vim config/production.yaml
 $ NODE_ENV=production NODE_CONFIG_DIR=/var/www/peertube-search-index/config node dist/server.js
 ```
+
+### Upgrade
+
+```
+cd /var/www/peertube-search-index && \
+  git pull origin master && \
+  yarn install --pure-lockfile && \
+  npm run build && \
+  sudo systemctl restart peertube-search-index.service
+```