replace markdownlint with codacy

Author: SarahAlidoost

.github/PULL_REQUEST_TEMPLATE.md

@@ -10,9 +10,9 @@ Please keep in mind that lesson maintainers are volunteers and it may be some ti
 - [ ] Read [CONTRIBUTING.md](https://github.com/ESMValGroup/tutorial/blob/master/CONTRIBUTING.md).
 - [ ] Create an [issue](https://github.com/ESMValGroup/tutorial/issues) to discuss what you are going to do.
 - [ ] Give this pull request a descriptive title.
-- [ ] If you are contributing to the lesson materials, please make sure the content conforms to the `Lesson development` section in [CONTRIBUTING.md](https://github.com/ESMValGroup/tutorial/blob/master/CONTRIBUTING.md) and does not contain any spelling or grammatical errors. 
-- [ ] Please use a `markdownlint` tool to check that your markdown files do not contain errors, bugs, or stylistic errors.
-- [ ] Preview changes on your own machine before pushing them to GitHub by running `make serve`, alternatively `make docker-serve`. Please see the `Previewing your changes locally` section in[CONTRIBUTING.md](https://github.com/ESMValGroup/tutorial/blob/master/CONTRIBUTING.md) for installation instructions.
+- [ ] If you are contributing to the lesson materials, please make sure the content conforms to the `Lesson development` section in [CONTRIBUTING.md](https://github.com/ESMValGroup/tutorial/blob/master/CONTRIBUTING.md) and does not contain any spelling or grammatical errors.
+- [ ] Preferably Codacy code quality checks pass. However, a few remaining hard to solve Codacy issues are still acceptable. Status can be seen below your pull request. If there is an error, click the link to find out why. If you suspect Codacy may be wrong, please ask by commenting.
+- [ ] Preview changes on your machine before pushing them to GitHub by running `make serve`, alternatively `make docker-serve`. Please see the `Previewing your changes locally` section in [CONTRIBUTING.md](https://github.com/ESMValGroup/tutorial/blob/master/CONTRIBUTING.md) for installation instructions.
 - [ ] All code instructions have been tested.
 
 ## More tasks for a new episode