Fix two issues in the rge(4) man page:
- The HARDWARE section stated "PCIe 1GB to 1GB Ethernet devices" which is incorrect. The RTL8125/8126/8127 chips support speeds from 1Gbps to 10Gbps. Correct the range.
- Note in DESCRIPTION that the rge(4) driver manages the PHY directly via the chip's OCP bus rather than using the miibus(4) interface.
Signed-off-by: Christos Longros <chris.longros@gmail.com>