Add note on dereferencing /aliases pointers

Add note on dereferencing /aliases pointers

Replace the "must quote special characters" note with a hint on
how to dereference /aliases pointers by omitting the leading "/".
This feature was introduced by Kumar Gala as a libfdt enhancement
in commit ed035708235332c3c117ee3bb1a426063f03cfcb.

Example:

=> fdt print /aliases
aliases {
        ethernet0 = "/qe@e0100000/ucc@2000";
        ethernet1 = "/qe@e0100000/ucc@3000";
        serial0 = "/soc8360@e0000000/serial@4500";
        serial1 = "/soc8360@e0000000/serial@4600";
        pci0 = "/pci@e0008500";
};
=> fdt print ethernet0
ucc@2000 {
        device_type = "network";
        compatible = "ucc_geth";
        cell-index = <0x1>;
        reg = <0x2000 0x200>;
        interrupts = <0x20>;
        interrupt-parent = <0x2>;
        local-mac-address = [00 00 00 00 00 00];
        rx-clock-name = "none";
        tx-clock-name = "clk9";
        phy-handle = <0x3>;
        phy-connection-type = "rgmii-id";
        pio-handle = <0x4>;
};

Signed-off-by: Gerald Van Baren <vanbaren@cideas.com>