Add missing file extensions in README previews

README.md

@@ -5,7 +5,7 @@ Android-related emojis for Slack
 | --- | --- | --- | --- |
 | <img src="androidgreen.png" width="100" height="100"> | <img src="androidaqua.png" width="100" height="100"> | <img src="androidblack.png" width="100" height="100"> | <img src="androidblue.png" width="100" height="100"> |
 | <img src="androidorange.png" width="100" height="100"> | <img src="androidpink.png" width="100" height="100"> | <img src="androidpride.png" width="100" height="100"> | <img src="androidpurple.png" width="100" height="100">|
-| <img src="androidred.png" width="100" height="100"> | <img src="androidgray.png" width="100" height="100"> | <img src="androidyellow.png" width="100" height="100"> | <img src="androidbrown" width="100" height="100"> |
-| <img src="androidhead.png" width="100" height="100"> | <img src="androidfixer.png" width="100" height="100"> | <img src="androidwave.png" width="100" height="100"> | <img src="androidcelebrate" width="100" height="100"> |
+| <img src="androidred.png" width="100" height="100"> | <img src="androidgray.png" width="100" height="100"> | <img src="androidyellow.png" width="100" height="100"> | <img src="androidbrown.png" width="100" height="100"> |
+| <img src="androidhead.png" width="100" height="100"> | <img src="androidfixer.png" width="100" height="100"> | <img src="androidwave.png" width="100" height="100"> | <img src="androidcelebrate.png" width="100" height="100"> |
 | <img src="androidstudio4.png" width="100" height="100"> | <img src="kotlinandroid2.png" width="100" height="100"> | <img src="kotlin.png" width="100" height="100"> | <img src="kotlinandroid.png" width="100" height="100"> |
 | <img src="androidtogether.png" width="100" height="100"> | <img src="androidalltogether.png" width="100" height="100"> | <img src="androidtogetherparty.gif" width="100" height="100"> | <img src="togethernotthesame.png" width="100" height="100"> |