updated docs

Author: Tomas Baca

docs/10-prerequisities/25-ros2/50-ros1-ros2-patterns/cmakelists.md

@@ -0,0 +1,34 @@
+---
+title: ROS2 CmakeLists
+pagination_label: ROS2 CmakeLists
+description: ROS2 CmakeLists
+---
+
+# ROS2 CmakeLists
+
+## `include_directories()`
+
+In ROS2 you have to explicitly list all the packages you are including from:
+```
+...
+include_directories(
+  ...
+  ${mrs_lib_INCLUDE_DIRS}
+  ${<some_other_package>_INCLUDE_DIRS}
+}
+```
+
+## exporting nodeletes (components)
+
+Components are declared in CmakeLists, instead of package.xml (like it was in ROS1):
+```
+rclcpp_components_register_nodes(MrsMultirotorSimulator_Simulator PLUGIN "mrs_multirotor_simulator::MultirotorSimulator" EXECUTABLE MrsMultirotorSimulator_Simulator)
+```
+
+## exporting pluginlib plugins
+
+You need to provide path to the `.xml` file with plugin description in CmakeLists, instaed of in `package.xml` like it was in ROS1:
+```
+# <package of the base class>, <relative path to the xml>
+pluginlib_export_plugin_description_file(mrs_uav_hw_api plugins.xml)
+```

docs/10-prerequisities/25-ros2/50-ros1-ros2-patterns/cpp_nodelets.md

@@ -1,5 +1,14 @@
 ---
-title: C++ componentts
-pagination_label: C++ componentes
-description: C++ components
+title: C++ components (nodelets)
+pagination_label: C++ componentes (nodelets)
+description: C++ components (nodelets)
 ---
+
+# `onInit()`
+
+There is no onInit() method like in ROS1.
+Now, you need to implement the constructor of `rclcpp::Node()`.
+
+However, you cannot obtain a pointer to the node in the constructor (while it is still running).
+Therefore, we create our own `initialize()` method as a one-shot timer that contain most of the init routines.
+We can use the constructor solely for starting the timer.