My version of it: at first I created a flat plane and made loop cuts in the middle, then split the plane into 3 separate faces by selecting the two edges in the center, right-clicking and choosing Edge Split. This will make the parenting to the armature easier.
Then I added an Armature > Single Bone at the bottom edge of the bottom face. I extruded it and adjusted the bones so that they fit to the faces.
After that I selected the plane object and the armature, hit Ctrl+P > Set Parent To > Armature Deform > With Empty Groups.
With the plane in Edit Mode I then selected the bottom face, selected the first vertex group for the bone at the bottom, made sure that Weight = 1 and clicked Assign. This I repeated for the second face and bone and of course for the third face and bone as well.
Now this will already work to bend the plane (as long as you restrict bending to the axis perpendicular to the face normal):
However, if I now add a Solidify Modifier, it will become obvious that I've split the faces (I've made it a bit thicker on purpose to show it better):
So in order to fix that, I put a Weld modifier between the Armature and the Solidify modifier. The position is important, because I want the mesh to be split for the bones, but it should be merged before I solidify it. Edit: I just tested it, after the faces are assigned to the bones it doesn't seem to matter if the Weld is before or after the Armature. I'll leave it here anyway in case of problems - the essential thing is, it has to be before the Solidify modifier.