fix nginx mode

The plus symbol (+) is not standard regular expressions, use extended regular expressions(`grep -E`) instead.

acme.sh

@@ -3163,9 +3163,9 @@ _checkConf() {
       FOUND_REAL_NGINX_CONF="$2"
       return 0
     fi
-    if cat "$2" | tr "\t" " " | grep "^ *include *.*;" >/dev/null; then
+    if cat "$2" | tr "\t" " " | grep -E "^ *include +.*;" >/dev/null; then
       _debug "Try include files"
-      for included in $(cat "$2" | tr "\t" " " | grep "^ *include *.*;" | sed "s/include //" | tr -d " ;"); do
+      for included in $(cat "$2" | tr "\t" " " | grep "^ *include +.*;" | sed "s/include //" | tr -d " ;"); do
         _debug "check included $included"
         if ! _startswith "$included" "/" && _exists dirname; then
           _relpath="$(dirname "$_c_file")"