How does Data Warehousing work in reverse? I've made many researches about data warehousing to learn more about it and I think I've grasped the idea. But I've read in an article or two that data warehousing allows you to do analysis on data brought from operational databases and then in some cases, the results are sent back to the operational databases where some data is updated and then used. 

Could someone give me an example where that might work?   

Because what I personally understood is that data warehousing allows to analyse the data in order to determine sales profitability or find patterns in sales, etc.

So is what I've read true? If so, are there examples?
This question is a bit too broad for a definitive answer, because there are endless possibilities for data to flow in all sorts of directions between various data stores. I also find it strange that the articles you read did not provide examples. 

One general application of a data warehouse feeding back information to an operational system would be analytics, calculated over historical data, affecting operational system rules, such as:


Consolidated (in a DWH) daily sales data from all stores of a retailer are used to determine certain product discounts in the point-of-sale system and goods delivery schedules in the logistics application.
Bank capital level per Basel rules are calculated in the DWH nightly and generate orders and trading limits in the trading application for the next day.
Customer churn prediction model of a telco tells their marketing call center who to spam-call next.