fix comments.

Signed-off-by: Tomoya.Fujita <[email protected]>

Co-authored-by: Chris Lalancette <[email protected]>

Author: fujitatomoya

rclcpp/include/rclcpp/executor.hpp

@@ -305,8 +305,7 @@ class Executor
    * If the time that waitables take to be executed is longer than the period on which new waitables
    * become ready, this method will execute work repeatedly until `max_duration` has elapsed.
    *
-   * \param[in] max_duration The maximum amount of time to spend executing work.
-   * `0` is block forever, must be greater than or equal to 0.
+   * \param[in] max_duration The maximum amount of time to spend executing work, must be >= 0.
    * \throw throw std::invalid_argument if max_duration is less than 0.
    * Note that spin_all() may take longer than this time as it only returns once max_duration has
    * been exceeded.

rclcpp/include/rclcpp/executors/static_single_threaded_executor.hpp

@@ -99,8 +99,8 @@ class StaticSingleThreadedExecutor : public rclcpp::Executor
 
   /// Static executor implementation of spin all
   /**
-   * This function will execute entities until timeout or no more work available.
-   * If timeout is equal to 0, it will block forever.
+   * This non-blocking function will execute entities until timeout (must be >= 0)
+   * or no more work available.
    * If new entities get ready while executing work available, they will be executed
    * as long as the timeout hasn't expired.
    *