[I18N] contributing, developer/tutorial: remove Transifex references

Odoo is transitioning away from Transifex. Remove links/references to it
and replace with new platform (internal Weblate server) links

closes #14159

X-original-commit: 78de46c
Signed-off-by: Tiffany Chang (tic) <[email protected]>

Author: ticodoo

content/contributing.rst

@@ -40,7 +40,7 @@ lists the most important of them.
      - Users of Odoo
    * - Translate Odoo
      - Translate the user interface and documentation of Odoo into different languages.
-     - * `Odoo project on Transifex <https://explore.transifex.com/odoo/>`_
+     - * `Odoo Translations <https://translate.odoo.com/>`_
      - Anyone fluent in multiple languages
    * - Contribute to the codebase
      - Submit pull requests to the Odoo GitHub repositories to fix bugs, add new features, or

content/developer/tutorials/backend.rst

@@ -1225,8 +1225,8 @@ file, and then derive the translated PO files. Many IDE's have plugins or modes
 for editing and merging PO/POT files.
 
 .. tip::
-   The Portable Object files generated by Odoo are published on `Transifex
-   <https://www.transifex.com/odoo/public/>`_, making it easy to translate the software.
+   The Portable Object files generated by Odoo are published on `Odoo's Translations Platform
+   <https://translate.odoo.com/>`_, making it easy to translate the software.
 
 .. code-block:: text