Clean up CLI help comments to reduce memory usage

[pwittich]

also get rid of some duplication
removed

• simple_sensor (removed code)
• watchdog task (commented out by #if 0)

Before:

(base) ➜  apollo_cm_mcu git:(master) make -j8  
  CC    cm_mcu.c
  LD    gcc/cm_mcu.axf 
  SZ    gcc/cm_mcu.axf
   text	   data	    bss	    dec	    hex	filename
  86989	   4628	  45856	 137473	  21901	gcc/cm_mcu.axf

After:

(base) ➜  apollo_cm_mcu git:(cli_help) make -j8 
  CC    cm_mcu.c
  LD    gcc/cm_mcu.axf 
  SZ    gcc/cm_mcu.axf
   text	   data	    bss	    dec	    hex	filename
  85789	   4628	  45856	 136273	  21451	gcc/cm_mcu.axf

text segment reduced by 1200 bytes.

[pkotamnives]

looks good, thank you Peter.