minor documentation updates to some commands

src/systemcmds/mixer/mixer.cpp

@@ -115,7 +115,7 @@ usage(const char *reason)
 ### Description
 Load or append mixer files to the ESC driver.
 
-Note that the driver must support the used ioctl's, which is the case on NuttX, but for example not on the RPi.
+Note that the driver must support the used ioctl's, which is the case on NuttX, but for example not on RPi.
 )DESCR_STR");
 
 

src/systemcmds/top/top.c

@@ -62,7 +62,7 @@ static void print_usage(void)
 {
 	PRINT_MODULE_DESCRIPTION("Monitor running processes and their CPU, stack usage, priority and state");
 
-	PRINT_MODULE_USAGE_NAME_SIMPLE("top", "system");
+	PRINT_MODULE_USAGE_NAME_SIMPLE("top", "command");
 	PRINT_MODULE_USAGE_COMMAND_DESCR("once", "print load only once");
 }