add some notes about internationalization support

Signed-off-by: Nicola Murino <[email protected]>

README.md

@@ -108,6 +108,7 @@ If you report an invalid issue or ask for step-by-step support, your issue will
 - Log files are accurate and they are saved in the easily parsable JSON format ([more information](./docs/logs.md)).
 - SFTPGo supports a [plugin system](./docs/plugins.md) and therefore can be extended using external plugins.
 - Infrastructure as Code (IaC) support using the [Terraform provider](https://registry.terraform.io/providers/drakkan/sftpgo/latest).
+- Partial (experimental) support for [internationalization](./docs/internationalization.md).
 
 ## Platforms
 
@@ -372,6 +373,8 @@ Thank you to [ysura](https://www.ysura.com/) for granting us stable access to a
 
 Thank you to [KeenThemes](https://keenthemes.com/) for granting us a custom license to use their amazing [Mega Bundle](https://keenthemes.com/products/templates-mega-bundle) for SFTPGo UI.
 
+Thank you to [Crowdin](https://crowdin.com/) for granting us an Open Source License.
+
 Thank you to [Incode](https://www.incode.it/) for helping us to improve the UI/UX.
 
 ## License

docs/internationalization.md

@@ -0,0 +1,15 @@
+# Internationalization
+
+SFTPGo uses the [i18next](https://www.i18next.com/) framework for managing translating phrases in WebAdmin and WebClient.
+
+Support for internationalization is experimental and may be removed in future releases. It mainly depends on the maintenance effort required and how useful this feature is for SFTPGo users. We currently only support English and Italian.
+
+The translations are available via [Crowdin](https://crowdin.com/project/sftpgo), who have granted us an open source license.
+
+Translating phrases is hard, even lexically correct translations in the wrong context can completely change the meaning and confuse users.
+Also, this is an ongoing effort, translations will be added, removed, updated in every release, even minor ones.
+
+For these reasons we don't accept contributions from casual users. If you want to add support for a new language we require:
+
+- you are a native speaker of the target language with the technical skills necessary to correctly contextualize SFTPGo translation phrases and/or a professional translator
+- you/your company ensure long-term commitment to the project and help the project to be long-term sustainable