My side projects on the other hand consist of F#, Elixir, C#, Python, Java, Unreal Engine playing around with Azure and Firebase. Just a giant list of things I build to 10 - 25% completion. There is this unreasonable and insatiable hunger to understand how EVERYTHING technical works, but only 80 years to learn it all in. So I end up buying books on Kivy (Python), Fsharp, I have 2 books on Elixir, one which I never even started etc etc. Send Help!
P.S. I even have a book on Openstack cause I was like "Wow, that sounds awesome, I must learn all about it." I haven't opened it.
P.P.S This obsession with knowing how to do everything also manifests outside of the digital world. I have a fridge full of kimchi I will never eat, and a laundry full of Mead I will never drink.
Now I find that the best docs are not written books, but online documentation. These days I'd say just play with it. Build an app. Start up the one box openstack devstack. People have gone through a lot of pains to make a simple dev environment work for a lot of different languages/platforms.
Once I get into it, it's less of an abstract idea, and more trying to do something. Having a toy project in mind also helps to build something useful. Over time, your knowledge will simply accrete.
I'd say I'm the opposite. Funnily enough, I'm envious of people who are a jack of all trades because they can choose the right tool for the job. I just do iOS development in my day job and side projects and although I love app development, I find the lack of knowledge on other tools limiting.