docs: revising comments and documents

- spi/slave.h: revise comments in pulic types section
- doc/sim.rst: minor formatting, add ways to escape cu

Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>

Documentation/platforms/sim/sim/boards/sim/index.rst

@@ -692,6 +692,7 @@ NOTES
      running C++ static initializers until NuttX has been initialized.
 
 fb
+--
 
 A simple configuration used for some basic (non-graphic) debug of the
 framebuffer character drivers using apps/examples/fb.
@@ -1115,14 +1116,14 @@ rpproxy and rpserver
 
   rpserver: Remote master(host) server process.
             rpserver contains all the real hardware configuration, such as:
-              1.Universal Asynchronous Receiver/Transmitter (UART).
-              2.Specific File System.
-              3.Network protocol stack and real network card device.
-              4....
+              1. Universal Asynchronous Receiver/Transmitter (UART).
+              2. Specific File System.
+              3. Network protocol stack and real network card device.
+              4. ...
 
 Rpmsg driver used in this example include:
 
-1.Rpmsg Syslog
+1. Rpmsg Syslog
 
     Source::
 
@@ -1250,6 +1251,8 @@ To use this example:
               1     1 224 FIFO     Kthread --- Waiting  Signal    00000000 002032 hpwork
               3     3 100 FIFO     Task    --- Running            00000000 004080 init
 
+      To switch back the console, type ``"~."`` in the cu session.
+
 3. RpmsgFS:
 
    Mount the remote file system via RPMSGFS, cu to proxy first::