Read not only .txt files

We should read jsonline files with key "text", otherwise look for .txt

assigned to @jgoluch

created branch 2-read-not-only-txt-files to address this issue

created merge request !3 (closed) to address this issue

mentioned in merge request !3 (closed)

mentioned in merge request !4 (merged)

mentioned in commit f6e486f4

closed with merge request !4 (merged)