i18n: add crowdin docker instructions

doc/dev/features/i18n.md

@@ -35,6 +35,44 @@ crowdin upload
 crowdin download
 ```
 
+## Crowdin Docker usage
+
+### Step 1: set up container (with sources from local git repo)
+
+```sh
+docker run -it --rm --name crowdin-cli \
+  -e CROWDIN_PERSONAL_TOKEN=${CROWDIN_PERSONAL_TOKEN} \
+  -v "./i18n/locale/en:/usr/crowdin-project/i18n/locale/en" \
+  crowdin/cli:latest
+```
+
+### Step 2: init crowdin.yml
+
+```sh
+crowdin init \
+    --token "${CROWDIN_PERSONAL_TOKEN}" \
+    --project-id "724667" \
+    --base-path "." \
+    --base-url "https://api.crowdin.com" \
+    --source "/i18n/locale/en/*.json" \
+    --translation "/i18n/locale/%locale%/%original_file_name%" \
+    --verbose
+```
+
+### Step 3: upload translations from container to PixivFE crowdin project
+
+```sh
+crowdin upload \
+  --verbose
+```
+
+### Step 4: download translations from PixivFE crowdin project to container
+
+```sh
+crowdin download \
+  --verbose
+```
+
 ## Crowdin Web UI usage
 
 Add new languages to translate in Settings > Languages.