decrease resolver errors level to error

src/core/ngx_resolver.c

diff --git a/src/core/ngx_resolver.c b/src/core/ngx_resolver.c
index 1df86fa..5b7bbbc 100644
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -138,7 +138,7 @@
     r->valid = 300;
 
     r->log = &cf->cycle->new_log;
-    r->log_level = NGX_LOG_ALERT;
+    r->log_level = NGX_LOG_ERR;
 
     if (addr) {
         uc = ngx_calloc(sizeof(ngx_udp_connection_t), cf->log);