Fix several typos (#1395)

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

plugin/template/README.md

@@ -50,7 +50,7 @@ Each resource record is a full-featured [Go template](https://golang.org/pkg/tex
 * `.Message` the complete incoming DNS message.
 * `.Question` the matched question section.
 
-The output of the template must be a [RFC 1035](https://tools.ietf.org/html/rfc1035) style resource record (commonly refered to as a "zone file").
+The output of the template must be a [RFC 1035](https://tools.ietf.org/html/rfc1035) style resource record (commonly referred to as a "zone file").
 
 **WARNING** there is a syntactical problem with Go templates and CoreDNS config files. Expressions
  like `{{$var}}` will be interpreted as a reference to an environment variable by CoreDNS (and

plugin/template/template_test.go

@@ -294,7 +294,7 @@ func TestHandler(t *testing.T) {
 	}
 }
 
-// TestMultiSection verfies that a corefile with mutliple but different template sections works
+// TestMultiSection verfies that a corefile with multiple but different template sections works
 func TestMultiSection(t *testing.T) {
 	ctx := context.TODO()
 
@@ -306,7 +306,7 @@ func TestMultiSection(t *testing.T) {
 		template IN A {
 			rcode REFUSED
 		}
-		# Fallthrough everyting IN TXT for test.
+		# Fallthrough everything IN TXT for test.
 		template IN TXT {
 			match "$^"
 			rcode SERVFAIL