Explicitely mention i18n not working on Alpine

Author: benoit74

README.md

@@ -50,6 +50,8 @@ sudo apt install libmagic1 wget ffmpeg \
 apk add ffmpeg gifsicle libmagic wget libjpeg
 ```
 
+**Nota:** i18n features do not work on Alpine, see https://github.com/openzim/python-scraperlib/issues/134 ; there is one corresponding test which is failing.
+
 # Contribution
 
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