You’re busy I get it, we all are. One of the most important things for a tech leader is not lost touch with the current trends and updates.
Actually, we can sum up the knowledge you should be up to date to the following

categories:
The stuff you know that you know you need to updated about
The stuff you know that you don’t know
The stuff you don’t know that you don’t know

“The Stuff you know that you know toy need to be updated about”

If you’re using ReactJS or .NET Core, you still have to make sure you’re up to date with the latest changes.
You might be missing the new functionality of C# 8 that can make you life easier or you’re might be struggling with bugs that were already fixed in the latest version.
How should I get the info?
I can assume you already part of some community , you already follow some sub-reddits or some blogs. If not , you should. In addition, sign up for updates, get email weekly summaries or even just make sure to check the landing page of your favorite framework once a week (make a reminder!)

“The stuff you know that you don’t know”

You might have heard that Python is getting a lot of attention since AI, Machine learning and Deep learning are on the rise or you heard that everyone is using Redis, but you know nothing about it. As a tech leader you should get at least an overview of the topic, take a note and if you think you might need it in the future, you’ll be able to dive it.
How should I get the info?
You should really try to follow the trends by googling about it from time to time. I find educational sites like “Pluralsight” very useful to get me started. Some of the courses offer great overview on various topics and are a good starting point to learn about new stuff.

“The stuff you don’t know that you don’t know”

Since we’re all very busy with our important tasks, we might not even know that Blockchain is a thing. Since software development is big and vast, we tend to try and focus on our own technologies. That might do for regular developers but if you’d like to be considered as a tech lead, you have to know what’s up with the outside world.

How should I get the info?

Check out the most popular meetups at meetup.com. Search for those you know nothing about, if you’re a back end guy, go for the front end ones, if you’re working in a corporate environment, check out the ones for startups. Try to attend one every couple of months.

As a tech leader, we are expected to have a deep understanding of our core technologies but adding tools to your “tool belt” is super important. You should always look for the next thing and encourage your developers to do the same.