add Instagram connection (discord#5876)

Author: cane

docs/resources/User.md

@@ -119,6 +119,7 @@ The connection object that the user has attached.
 | epicgames       | Epic Games          |
 | facebook        | Facebook            |
 | github          | GitHub              |
+| instagram       | Instagram           |
 | leagueoflegends | League of Legends   |
 | paypal          | PayPal              |
 | playstation     | PlayStation Network |