Fix case of all headings

doc/user/application_security/coverage_fuzzing/index.md

@@ -97,7 +97,7 @@ Each fuzzing step outputs these artifacts:
   - `crashes`: Holds all crash events the current job encountered as well as those not fixed in
     previous jobs.
 
-### Types of Fuzzing Jobs
+### Types of fuzzing jobs
 
 There are two types of jobs:
 
@@ -172,13 +172,13 @@ Here's an example coverage fuzzing report:
 }
 ```
 
-### Additional Configuration
+### Additional configuration
 
 The `gitlab-cov-fuzz` command passes all arguments it receives to the underlying fuzzing engine. You
 can therefore use all the options available in that fuzzing engine. For more information on these
 options, see the underlying fuzzing engine's documentation.
 
-### Offline Environment
+### Offline environment
 
 To use coverage fuzzing in an offline environment, follow these steps: