Use design-time tools to see sample text without leaving hardcoded text
Mark null content descriptions to handle lint warnings

Please note these are null because they are dynamic images whose proper description label should already be covered by the user name in the layouts
Ignore lint CompoundDrawable suggestion

It's not appropriate here; we want to set our own sizes as the avatars provided by Github can be much, much bigger
Use sp instead of dp

This supports accessibility a bit better.
Use marginEnd to support RTL layouts
Restore ActionBar and add a refresh action.