glTexImage3D width supports at least 16 texels

[Docter60]

The current gl4 documentation says the width supported in glTexImage3D is at least 16. Is it supposed to say at least 256 instead?

[NogginBops]

Most of these values seem out of date. OpenGL 4.6 spec allows the height, width and depth to be at least 2048.
As the refpages say they are 4.5 I'm going to update them to that standard.