Documentation additions for PC style clock

Source/Doc/Hardware.md

@@ -2318,6 +2318,7 @@ Note:
 | DSRTC     | Maxim DS1302 Real-Time Clock w/ NVRAM                  |
 | EZ80RTC   | eZ80 Real-Time Clock                                   |
 | INTRTC    | Interrupt-based Real Time Clock                        |
+| PCRTC     | MC146818/DS1285/DS12885 PC style                       |
 | PCF       | PCF8584-based I2C Real-Time Clock                      |
 | RP5C01    | Ricoh RPC01A Real-Time Clock w/ NVRAM                  |
 | SIMRTC    | SIMH Simulator Real-Time Clock                         |

Source/Doc/SystemGuide.md

@@ -1416,6 +1416,7 @@ unit.  The table below enumerates these values.
 | RTCDEV_DS7      | 0x04   | Maxim DS1307 PCF I2C RTC w/ NVRAM        | ds7rtc.asm  |
 | RTCDEV_RP5      | 0x05   | Ricoh RPC01A Real-Time Clock w/ NVRAM    | rp5rtc.asm  |
 | RTCDEV_EZ80     | 0x07   | eZ80 on-chip RTC                         | ez80rtc.asm |
+| RTCDEV_PC       | 0x08   | MC146818/DS1285/DS12885 RTC w/ NVRAM     | pcrtc.asm   |
 
 The time functions to get and set the time (RTCGTM and RTCSTM) require a
 6 byte date/time buffer in the following format. Each byte is BCD