chore: add @Kavindu-Dodan to CODEOWNERS (#377)

@Kavindu-Dodan has contributed multiple significant changes and
proposals to flagd:

- multiple refactors: #291,
#307
- ci/security improvements:
#338,
#337
- architectural proposals (some of which got some attention from outside
parties!): open-feature/ofep#45,
open-feature/flagd-schemas#78,
#249 (comment)
- load testing: #225
- documentation improvements

For these reasons, I believe he should be made a CODEOWNER in this
repository.

NOTE: before this is merged, @Kavindu-Dodan should be added with at
least `maintainer` permissions to the repo.

Signed-off-by: Todd Baert <toddbaert@gmail.com>

CODEOWNERS

@@ -1,3 +1,3 @@
 # These owners will be the default owners for everything in
 # the repo. Unless a later match takes precedence
-* @AlexsJones @james-milligan @toddbaert
+* @AlexsJones @james-milligan @toddbaert @kavindu-dodan