Clarify voltage of device_detect and power_on_reset signals

Table 21, Electrical signal specifications, is unclear about the voltage of device_detect and power_on_reset. Note 2 of Table 21 refers to Table 4, but Table 4 only lists signals within a channel, not the AUX signals device_detect and power_on_reset.
Suggest note 2 be changed to:
2. “Gen2 Mode low-speed signals” includes all signals of Table 4 except TX, RX, ns_fwd_clk, ns_fwd_clkb, fs_fwd_clk, fs_fwd_clkb. "Gen1 Mode signals" includes the signals of the AUX Block of section 1.3.4.4.

The result is that power_on_reset and device_detect are signals with typical output swing of 0.9V.

Review Table 21 and its Note 2, then compare the referenced Table 4 with the AUX Block in section 1.3.4.4. Update the note so the signal groups and voltage interpretation for device_detect and power_on_reset are unambiguous.

Written by the indexing model from the issue text.