Module documentation: switch to Markdown

src/modules/events/send_event.cpp

@@ -199,6 +199,7 @@ int SendEvent::print_usage(const char *reason)
 
 	PRINT_MODULE_DESCRIPTION(
 		R"DESCR_STR(
+### Description
 Background process running periodically on the LP work queue to perform housekeeping tasks.
 It is currently only responsible for temperature calibration.
 

src/modules/logger/logger.cpp

@@ -143,21 +143,26 @@ int Logger::print_usage(const char *reason)
 
 	PRINT_MODULE_DESCRIPTION(
 		R"DESCR_STR(
-System logger which logs a (configurable) set of uORB topics and system printf messages
+### 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,
 tuning, replay and crash analysis.
 
 It supports 2 backends:
 - Files: write ULog files to the file system (SD card)
 - MAVLink: stream ULog data via MAVLink to a client (the client must support this)
+
 Both backends can be enabled and used at the same time.
 
+### Implementation
 The implementation uses two threads:
 - The main thread, running at a fixed rate (or polling on a topic if started with -p) and checking for
-data updates
+  data updates
 - The writer thread, writing data to the file
+
 In between there is a write buffer with configurable size. It should be large to avoid dropouts.
 
+### Examples
 Typical usage to start logging immediately:
 $ logger start -e -t
 

src/modules/mavlink/mavlink_main.cpp

@@ -2703,19 +2703,23 @@ static void usage()
 
 	PRINT_MODULE_DESCRIPTION(
 		R"DESCR_STR(
+### Description
 This module implements the MAVLink protocol, which can be used on a Serial link or UDP network connection.
 It communicates with the system via uORB: some messages are directly handled in the module (eg. mission
 protocol), others are published via uORB (eg. vehicle_command).
 
 Streams are used to send periodic messages with a specific rate, such as the vehicle attitude.
 When starting the mavlink instance, a mode can be specified, which defines the set of enabled streams with their rates.
-For a running instance, streams can be configured via 'mavlink stream' command.
+For a running instance, streams can be configured via `mavlink stream` command.
 
 There can be multiple independent instances of the module, each connected to one serial device or network port.
 
-The implementation uses 2 threads, a sending and a receiving thread.
+### Implementation
+The implementation uses 2 threads, a sending and a receiving thread. The sender runs at a fixed rate and dynamically
+reduces the rates of the streams if the combined bandwidth is higher than the configured rate (`-r`) or the
+physical link becomes saturated. This can be checked with `mavlink status`, see if `rate mult` is less than 1.
 
-Example usage:
+### Examples
 Start mavlink on ttyS1 serial with baudrate 921600 and maximum sending rate of 80kB/s:
 $ mavlink start -d /dev/ttyS1 -b 921600 -m onboard -r 80000