diff --git a/README.md b/README.md
index 7185d85..3941524 100644
--- a/README.md
+++ b/README.md
@@ -25,6 +25,10 @@ $ cd client && npm run serve
 
 Then open http://localhost:8080.
 
+### Add locale
+
+Add the locale in `client/src/main.ts` and `client/Makefile`. Then update translations.
+
 ## Production
 
 Install dependencies:
@@ -34,14 +38,28 @@ Install dependencies:
 In the root of the cloned repo:
 
 ```terminal
+$ git clone https://framagit.org/framasoft/peertube/search-index.git /var/www/peertube-search-index
+$ cd /var/www/peertube-search-index
 $ git submodule update --init --recursive
 $ yarn install --pure-lockfile
 $ npm run build
 $ cp config/default.yaml config/production.yaml
 $ vim config/production.yaml
-$ node dist/server.js
+$ NODE_ENV=production NODE_CONFIG_DIR=/var/www/peertube-search-index/config node dist/server.js
 ```
 
-## Add locale
+### Mapping migration
+
+To update Elastic Search index mappings without downtime, run another instance of the search indexer
+using the same configuration that the main node. You just have to update `elastic-search.indexes.*` to use new index names.
+
+```
+$ cd /var/www/peertube-search-index
+$ cp config/production.yaml config/production-1.yaml
+$ vim config/production-1.yaml
+$ NODE_ENV=production NODE_APP_INSTANCE=1 NODE_CONFIG_DIR=/var/www/peertube-search-index/config node dist/server.js
+```
+
+After a while the new indexes will be filled. You can then stop the second indexer, update `config/production.yaml` to use
+the new index names and restart the main index.
 
-Add the locale in `client/src/main.ts` and `client/Makefile`. Then update translations.