Weblate: Add support for read only strings

**Your Godot version:**
3.2 stable

**Issue description:**
I started to contribute to the pt_BR localization of Godot documentation on Weblate and realized that some strings can have no translations. It's my first time using Weblate so I don't know how to handle these cases properly.

As a example, the following documentation page
https://docs.godotengine.org/en/stable/getting_started/editor/default_key_mapping.html
has a lot of strings that have no translations (e.g. the keyboard keys and the respective Editor setting).

So I started to copy the translation but noticed that maybe these strings are left blank on purpose. I should like someone to explain to me the appropriate way :)

After a research, I found that Weblate 3.10 added support for read only strings:
https://github.com/WeblateOrg/weblate/issues/743
https://github.com/WeblateOrg/weblate/blob/master/docs/changes.rst#weblate-310

Is it possible to add support for read-only strings on Godot documentation?