I randomly get a green or red blinking light from near the earpiece of my phone. What do they mean? Where are they documented? I could find nothing in the user manual.
The lights could be trying to tell you a number of different things.
[FRONT SIDE LED]
A flashing green light could be telling you you received a new text, an email, a phone call, an alarm clock reminder (doubtful since you may not have learned how to set one yet), or a calendar notification (doubtful like the alarm clock I'm guessing you haven't set one yet).
When you've got a red light its probably telling you that you should plug in the phone to charge. Solid red probably means low battery. Flashing red could mean battery level is critically low, or may happen during early charging. Solid green usually means a phone is fully charged.
The basic settings area as well as some third party apps can be used to change how the lights behave and what color they are...
The user manual is here:
On pg. 36 there is an off hand mention of notification lights being dependent on settings... and a notification of some kind would be my first guess. Browsing the manual I didn't see anything specific for the device and indicator lights, but Android_Optimizer has given good possibilities.
Settings | Display | Notification Light. You can turn the feature ON. Then press Notification Light, and you can select what events you are notified via the LED as was mentioned by Android_Optimizer. You can also download an app like LightFlow and have other features.