[Training course 1] Group articles & concepts around topics in L2

[dibaunaumh]

Add actions to the 1st training course to group together articles & concepts around topics. That requires:

• Run topic modeling on batches of articles
• Mark articles based on their related topic
• Classify the topics to label them with names
• Lookup the location of topics based on previous day (if exists)
• Pull concepts from lower floors & group around topics
• Pull articles from lower floors & group around topics

[dibaunaumh]

High-level design started here