Add podcast section

[SiqingYu]

Many developers like listening to podcasts. I think podcasts are excellent media for both experienced and new Linux users and to subscribe. A podcast list should include some of the best podcasts in the Linux community.

[inputsh]

Mirroring my comment from #39 to save you a click:

That would indeed be awesome material to have!

Unfortunately, I'm not much of a podcast kind of guy, so if someone else wants to kick off the category, you're more then welcome to!

[SiqingYu]

The list I recommend. https://github.com/aleksandar-todorovic/awesome-linux/pull/60