Adding c:\program files\telegraf\telegraf.conf

this will now be the default config file location on windows, basically
it is the windows equivalent of /etc/telegraf/telegraf.conf

also updating the changelog

closes #1543

internal/config/config.go

@@ -9,6 +9,7 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"runtime"
 	"sort"
 	"strings"
 	"time"
@@ -432,6 +433,9 @@ func getDefaultConfigPath() (string, error) {
 	envfile := os.Getenv("TELEGRAF_CONFIG_PATH")
 	homefile := os.ExpandEnv("${HOME}/.telegraf/telegraf.conf")
 	etcfile := "/etc/telegraf/telegraf.conf"
+	if runtime.GOOS == "windows" {
+		etcfile = `C:\Program Files\Telegraf\telegraf.conf`
+	}
 	for _, path := range []string{envfile, homefile, etcfile} {
 		if _, err := os.Stat(path); err == nil {
 			log.Printf("Using config file: %s", path)