Merge pull request #2 from ohsawa1204/doc-update-readme

docs(README.md): minor fixes

README.md

@@ -261,7 +261,7 @@ Below is the list of listener nodes included in the `waitset_examples` package.
 - `timer_listener_single`
   - behavior
     - It has a cyclic timer to execute a callback function in which a `/chatter` message is obtained from Subscription Queue after arrival of a message is checked with `rlcpp::WaitSet`
-    - It print the obtained message by `RCLCPP_INFO`
+    - It prints the obtained message by `RCLCPP_INFO`
   - option
     - `update_frequency` (float)
       - specify timer frequency
@@ -283,7 +283,7 @@ Below is the list of listener nodes included in the `waitset_examples` package.
 - `timer_listener_single_wait_some_period`
   - behavior
     - It has a cyclic timer to execute a callback function in which a `/chatter` message is obtained from Subscription Queue after arrival of a message is checked with `rlcpp::WaitSet`
-    - Duration for timeout is given as the given as the argument of `wait`
+    - Duration for timeout is given as the argument of `wait`
     - It prints out string data in a incoming message if it receives the message by the duration
     - Otherwise it prints out that timeout occurs during waiting a message
   - option