Can you please add a comment similar to the ones in Settings explaining what this substitution is, at least for the first string and adding this is valid for all the -header strings? Example

```
# LOCALIZATION NOTE (camera-resolution-header): if you leave the original 
# en-US value "{{camera-resolution}}" in the following string, the localization
# will be automatically picked from the existing string with ID "camera-resolution". 
# If you need to adapt your localization to the reduced space available in
# headers, you can use a shorter string here. The same comment is valid for
# all -header strings using a {{variable}}. 
```