Add OGG sample file

tag_test.go

@@ -59,10 +59,12 @@ func TestReadFrom(t *testing.T) {
 		"with_tags/sample.id3v24.mp3": fullMetadata,
 		"with_tags/sample.m4a":        fullMetadata,
 		"with_tags/sample.mp4":        fullMetadata,
+		"with_tags/sample.ogg":        fullMetadata,
 		"without_tags/sample.flac":    emptyMetadata,
 		"without_tags/sample.m4a":     emptyMetadata,
 		"without_tags/sample.mp3":     emptyMetadata,
 		"without_tags/sample.mp4":     emptyMetadata,
+		"without_tags/sample.ogg":     emptyMetadata,
 	}
 
 	for path, metadata := range testdata {

testdata/README.md

@@ -1,3 +1,20 @@
 # testdata
 
 Samples files come from [here](http://techslides.com/sample-files-for-development)
+
+To write tags to files you can use `lltag`:
+
+```sh
+lltag sample.* \
+  -a "Test Artist" \
+  -t "Test Title" \
+  -A "Test Album" \
+  -n "3" \
+  -g "Jazz" \
+  -d "2000" \
+  -c "Test Comment" \
+  --tag ALBUMARTIST="Test AlbumArtist" \
+  --tag COMPOSER="Test Composer"\
+  --tag DISCNUMBER="02" \
+  --tag TRACKTOTAL="06"
+```