update(docs): add how to manage translations

docs/development/translation.md

@@ -0,0 +1,24 @@
+# Manage translations
+
+## Requirements
+
+Qt Linguist tools are used to manage translations. Typically on Ubuntu:
+
+```bash
+sudo apt install qttools5-dev-tools
+```
+
+## Workflow
+
+1. Update `.ts` files:
+
+    ```bash
+    pylupdate5 -verbose profile_manager/resources/i18n/plugin_translation.pro
+    ```
+
+2. Translate your text using QLinguist or directly into `.ts` files.
+3. Compile it:
+
+    ```bash
+    lrelease profile_manager/resources/i18n/*.ts
+    ```