Is that a lot? Not really. 0.1 μSv is also known as BED (Banana Equivalent Dose)
Here is a great video to get radiation into perspective:
Short summary of this really well written article:
The defining feature of MVP is that data is communicated back to the view imperatively.
HEAD is a pointer to a commit (usually master) so when you checkout your repository the commit which HEAD points at will be checked out. Usually you'd want it if when checking out you want a different branch or tag to be checked out.
You can take a look at what it's pointing out by issuing the following command:
And you'll probably see something like the following: origin/HEAD -> origin/master
You can delete HEAD if you don't need it (although it doesn't do any harm being there) by issuing the following command:
Note: on github there is already an checkbox you can check under Settings > Options.
The two following medium articles are explaining the best strategyHow to export clean .svg icons with Sketch