Cross-reference concept exercise file information

[Docs] Cross-reference concept exercise file information

Author: ErikSchierboom

reference/implementing-a-concept-exercise.md

@@ -19,7 +19,7 @@ As this document is generic, the following placeholders are used:
 
 Before implementing the exercise, please make sure you have a good understanding of what the exercise should be teaching (and what not). This information can be found in the exercise's GitHub issue.
 
-To implement a concept exercise, the following files need to be created:
+To implement a concept exercise, the following files need to be added:
 
 ```
 languages
@@ -52,15 +52,15 @@ languages
 
 ```
 
-## Step 1: add track-specific files
+## Step 1: Add code files
 
 These are files specific to the Python track:
 
 - `src/<NAME>.py`: the stub implementation file, which is the starting point for students to work on the exercise.
 - `test/<NAME>_test.py`: the test suite.
 - `.meta/example.py`: an example implementation that passes all the tests.
 
-## Step 2: add common files
+## Step 2: Add documentation files
 
 How to create the files common to all tracks is described in the [how to implement a concept exercise document][how-to-implement-a-concept-exercise].