Add a dedicated translator guide document

Translation of the strings of the Arduino IDE UI is a valuable contribution which helps to make Arduino accessible to
everyone around the world.

Localization of the Arduino-specific strings of the IDE is done in the "Arduino IDE 2.0" project on Transifex.
Previously, the "Translation" row in the contribution methods summary table in the contributor guide entry page simply
linked to that project.

Arduino IDE also uses localized strings from several other sources:

- VS Code language packs
- Arduino CLI

Users may notice unlocalized strings or errors or areas for improvement in the existing translations and wish to
contribute translations. For this reason, it is important to also provide instructions for contributing to those other
localization data sources. The contribution methods summary table can not effectively accommodate that additional
content so a dedicated document is added for the purpose. This will also allow linking directly to that document from
related documentation or conversations.

docs/CONTRIBUTING.md

@@ -11,14 +11,14 @@ There are several ways you can get involved:
 | - Support<br/>- Question<br/>- Discussion | Post on the [**Arduino Forum**][forum]                                           |
 | - Bug report<br/>- Feature request        | Issue report (see the guide [**here**][issues])                                  |
 | Testing                                   | Beta testing, PR review (see the guide [**here**][beta-testing])                 |
-| Translation                               | [Transifex project][translate]                                                   |
+| Translation                               | See the guide [**here**][translate]                                              |
 | - Bug fix<br/>- Enhancement               | Pull request (see the guide [**here**][prs])                                     |
 | Monetary                                  | - [Donate][donate]<br/>- [Sponsor][sponsor]<br/>- [Buy official products][store] |
 
 [forum]: https://forum.arduino.cc
 [issues]: contributor-guide/issues.md#issue-report-guide
 [beta-testing]: contributor-guide/beta-testing.md#beta-testing-guide
-[translate]: https://www.transifex.com/arduino-1/ide2/dashboard/
+[translate]: contributor-guide/translation.md#translator-guide
 [prs]: contributor-guide/pull-requests.md#pull-request-guide
 [donate]: https://www.arduino.cc/en/donate/
 [sponsor]: https://github.com/sponsors/arduino

docs/contributor-guide/translation.md

@@ -0,0 +1,33 @@
+# Translator Guide
+
+The text of the Arduino IDE interface is translated into several languages. The language can be selected in the dialog opened via **File > Preferences** in the Arduino IDE menus (**Arduino IDE > Preferences** for macOS users).
+
+Translating text and improving on existing translations is a valuable contribution to the project, helping make Arduino accessible to everyone.
+
+The translations for the text found in the Arduino IDE come from several sources:
+
+## Arduino IDE Text
+
+Translations of Arduino IDE's text is done in the "**Arduino IDE 2.0**" project on the **Transifex** localization platform:
+
+https://explore.transifex.com/arduino-1/ide2/
+
+## Base Application Text
+
+Arduino IDE leverages the localization data available for the [**VS Code**](https://code.visualstudio.com/) editor to localize shared UI text. This reduces the translation work required to add a new language to the text specific to the Arduino IDE project.
+
+For this reason, some of Arduino IDE's text is not found in the **Transifex** project. Suggestions for corrections or improvement to this text are made by submitting an issue to the `microsoft/vscode-loc` GitHub repository.
+
+Before submitting an issue, please check the existing issues to make sure it wasn't already reported:<br />
+https://github.com/microsoft/vscode-loc/issues
+
+After that, submit an issue here:<br />
+https://github.com/microsoft/vscode-loc/issues/new
+
+## Arduino CLI Text
+
+The [**Arduino CLI**](https://arduino.github.io/arduino-cli/latest/) tool handles non-GUI operations for the Arduino IDE. Some of the text printed in the "**Output**" panel and in notifications originates from **Arduino CLI**.
+
+Translations of Arduino CLI's text is done in the "**Arduino CLI**" Transifex project:
+
+https://explore.transifex.com/arduino-1/arduino-cli/