Add localisation files to prettierignore (#290)

The language specific files `en.*.json` are produced by the localisation builds, and not by us. Remove them from prettier.

Signed-off-by: Richard Edgar <riedgar@microsoft.com>

.prettierignore

@@ -4,4 +4,6 @@
 /coverage
 _NOTICE.md
 raiwidgets/raiwidgets/widget
-raiwidgets/raiwidgets/error-analysis/python/error_analysis/widget/static/
+
+# Language specific files are not generated by us
+libs/localization/src/lib/en.*.json