add ctime and ctime_r to date_and_time documentation

closes llvm#108664

Author: zimirza

libc/docs/date_and_time.rst

@@ -55,6 +55,10 @@ Implementation Status
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | asctime_r           | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
+| ctime               | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
++---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
+| ctime_r             | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
++---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | clock               | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+
 | clock_getcpuclockid |         |         |         |                 |         |         |         |         |         |         |         |         |