Add doc comment to HandleHealthCheck method

internal/handlers/healthcheck.go

@@ -4,6 +4,7 @@ import (
 	"net/http"
 )
 
+// HandleHealthCheck returns a handler for the health check endpoint.
 func (s *Handlers) HandleHealthCheck() http.HandlerFunc {
 	return func(w http.ResponseWriter, _ *http.Request) {
 		resp := s.hc.Healthcheck()