Improve documentation about generation coverage report

INSTALL.md

@@ -115,7 +115,7 @@ meson test --gdb <testname>
 
 ### Producing a coverage report
 
-First, configure the build with this command.
+First, ensure that either `gcovr` or `lcov` is installed as a dependency for generating coverage reports.
 
 ```
 cd <name of the build directory>
@@ -172,6 +172,12 @@ meson test fuzz_round_trip\ 10\ min --verbose
 
 Happy fuzzing! 🚀
 
+To reset the coverage data, use the following command:
+
+```
+ninja clean-gcda
+```
+
 ## Documentation 
 ### External dependencies
 To generate the documentation you need the [Doxygen](https://www.doxygen.nl/index.html) program.