Like a friend, we spent a very long time looking for manuals for configuring IPTables, it took us a lot of time to search and study material, and time, as everyone knows, is money.
Then I had the idea of creating a "manual - center." Those. Provide all background information about everything - games, OS, programming languages, and more. ')
In each category, you can write not only textbooks, but also free articles. Anyone can edit a textbook or an article (like WiKi).