Add ignoring code cov any files named test_ (#1691)

* Add ignoring code cov any files named test_

* Update slack URL

* Update codecov.yml

README.md

@@ -10,7 +10,7 @@ For detailed instructions on how to:
 - [Navigation Plugins](https://navigation.ros.org/plugins/index.html)
 - [Contribute](https://navigation.ros.org/contribute/index.html)
 
-Please visit our [documentation site](https://navigation.ros.org/). [Please visit our community Slack here](navigation2.slack.com).
+Please visit our [documentation site](https://navigation.ros.org/). [Please visit our community Slack here](https://navigation2.slack.com).
 
 | Service | Dashing | Eloquent | Master |
 | :---: | :---: | :---: | :---: |

codecov.yml

@@ -4,3 +4,5 @@ fixes:
 ignore:
   - "*/**/test/*"  # ignore package test directories, e.g. nav2_dwb_controller/costmap_queue/tests
   - "*/test/**/*" # ignore package  test directories, e.g. nav2_costmap_2d/tests
+  - "**/test_*.*" # ignore files starting with test_ e.g.  nav2_map_server/test/test_constants.cpp
+  - "**/*_tests.*" # ignore files ending with _tests e.g. nav2_voxel_grid/test/voxel_grid_tests.cpp