* Update feature_rgb_matrix.md
Added more clarification on how to use a newly created rgb effect as it was unclear that the prefix 'RGB_MATRIX_CUSTOM_' had to be added.
Also included an example consistent with the documentation example.
* Update docs/feature_rgb_matrix.md
Co-authored-by: Ryan <[email protected]>
* Update docs/feature_rgb_matrix.md
Co-authored-by: Joel Challis <[email protected]>
Co-authored-by: Ryan <[email protected]>
Co-authored-by: Joel Challis <[email protected]>
