minor documentation updates to some commands

src/modules/logger/logger.cpp

@@ -145,7 +145,7 @@ int Logger::print_usage(const char *reason)
 		R"DESCR_STR(
 ### Description
 System logger which logs a configurable set of uORB topics and system printf messages
-(warnings and errors) to ULog files. These can be used for system and flight performance evaluation,
+(`PX4_WARN` and `PX4_ERR`) to ULog files. These can be used for system and flight performance evaluation,
 tuning, replay and crash analysis.
 
 It supports 2 backends:

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");
 }