Change links from index.ros.org -> docs.ros.org (#539)

And make a few other minor updates while we are in here.

Signed-off-by: Chris Lalancette <clalancette@openrobotics.org>

README.md

@@ -1,11 +1,10 @@
 # ROS 2 Middleware Implementation for eProsima's Fast DDS
 
-`rmw_fastrtps` constitutes __[ROS 2](https://index.ros.org/doc/ros2/) default middleware implementation__, providing an interface between ROS 2 and [eProsima's](https://www.eprosima.com/index.php) [Fast DDS](https://github.com/eProsima/Fast-DDS) middleware.
+`rmw_fastrtps` is a [ROS 2](https://docs.ros.org/en/rolling) middleware implementation, providing an interface between ROS 2 and [eProsima's](https://www.eprosima.com/index.php) [Fast DDS](https://github.com/eProsima/Fast-DDS) middleware.
 
 ## Getting started
 This implementation is available in all ROS 2 distributions, both from binaries and from sources.
-You do not need to do anything in order to use Fast DDS as your ROS 2 middleware layer (since it is the default implementation).
-However, you can still specify it in two different ways:
+You can specify Fast DDS as your ROS 2 middleware layer in two different ways:
 
 1. Exporting `RMW_IMPLEMENTATION` environment variable:
     ```bash
@@ -28,7 +27,7 @@ You can however set it to `rmw_fastrtps_dynamic_cpp` using the environment varia
 
 ## Advance usage
 
-ROS 2 only allows for the configuration of certain middleware QoS (see [ROS 2 QoS policies](https://index.ros.org/doc/ros2/Concepts/About-Quality-of-Service-Settings/#qos-policies)).
+ROS 2 only allows for the configuration of certain middleware QoS (see [ROS 2 QoS policies](https://docs.ros.org/en/foxy/Concepts/About-Quality-of-Service-Settings.html#qos-policies)).
 In addition to ROS 2 QoS policies, `rmw_fastrtps` sets two more Fast DDS configurable parameters:
 
 * History memory policy: `PREALLOCATED_WITH_REALLOC_MEMORY_MODE`
@@ -41,7 +40,7 @@ However, `rmw_fastrtps` offers the possibility to further configure Fast DDS:
 
 ### Change publication mode
 
-Fast DDS feats two different [publication modes](https://fast-dds.docs.eprosima.com/en/v2.1.0/fastdds/dds_layer/core/policy/eprosimaExtensions.html?highlight=synchronous#publishmodeqospolicykind): synchronous and asynchronous.
+Fast DDS features two different [publication modes](https://fast-dds.docs.eprosima.com/en/v2.1.0/fastdds/dds_layer/core/policy/eprosimaExtensions.html?highlight=synchronous#publishmodeqospolicykind): synchronous and asynchronous.
 To learn more about the implications of choosing one mode over the other, please refer to [DDS: Asynchronous vs Synchronous Publishing](https://www.eprosima.com/index.php/resources-all/performance/dds-asynchronous-vs-synchronous-publishing):
 
 `rmw_fastrtps` offers an easy way to change Fast DDS' publication mode without the need of defining a XML file. That is environment variable `RMW_FASTRTPS_PUBLICATION_MODE`.

rmw_fastrtps_cpp/QUALITY_DECLARATION.md

@@ -101,7 +101,7 @@ Unit, integration, and system tests higher up in the stack, such as those found
 
 ### Coverage [4.iii]
 
-`rmw_fastrtps_cpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#coverage), and opts to use branch coverage instead of line coverage.
+`rmw_fastrtps_cpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#code-coverage), and opts to use branch coverage instead of line coverage.
 
 This includes:
 

rmw_fastrtps_shared_cpp/QUALITY_DECLARATION.md

@@ -101,7 +101,7 @@ Unit, integration, and system tests for `rmw_fastrtps_cpp` and `rmw_fastrtps_dyn
 
 ### Coverage [4.iii]
 
-`rmw_fastrtps_shared_cpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://index.ros.org/doc/ros2/Contributing/Developer-Guide/#coverage), and opts to use branch coverage instead of line coverage.
+`rmw_fastrtps_shared_cpp` follows the recommendations for ROS Core packages in the [ROS 2 Developer Guide](https://docs.ros.org/en/rolling/Contributing/Developer-Guide.html#code-coverage), and opts to use branch coverage instead of line coverage.
 
 This includes: