added error message

documents/biblatex-mwe/README.md

@@ -1 +1,12 @@
 Example was created by matth on [tex.stackexchange.com](http://tex.stackexchange.com/a/34136/5645).
+
+Currently, this does not work:
+
+```
+Output written on biblatex-mwe.pdf (1 page, 24234 bytes).
+Transcript written on biblatex-mwe.log.
+biber biblatex-mwe.tex
+data source /tmp/par-6d6f6f7365/cache-c0ce847d97518634a1d34dec94f97d899cf5032b/inc/lib/Biber/LaTeX/recode_data.xml not found in .
+INFO - This is Biber 1.5
+INFO - Logfile is 'biblatex-mwe.tex.blg'
+```