runtime(json5): Add new ftplugin (#13385)

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index a75f00d..ccb36b3 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -163,6 +163,8 @@
 runtime/ftplugin/j.vim			@glts
 runtime/ftplugin/javascript.vim		@dkearns
 runtime/ftplugin/javascriptreact.vim	@dkearns
+runtime/ftplugin/json.vim		@dbarnett
+runtime/ftplugin/json5.vim		@dkearns
 runtime/ftplugin/jsonc.vim		@izhakjakov
 runtime/ftplugin/julia.vim		@carlobaldassi
 runtime/ftplugin/kconfig.vim		@chrisbra