Documents expected emoji format

Author: onerandomusername

pydis_site/apps/content/resources/guides/pydis-guides/contributing/sir-lancebot/env-var-reference.md

@@ -32,7 +32,7 @@ Additionally, you may find the following environment variables useful during dev
 | `REDIS_PASSWORD` | |
 | `USE_FAKEREDIS` | If the FakeRedis module should be used. Set this to true if you don't have a Redis database setup. |
 | `BOT_SENTRY_DSN` | The DSN of the sentry monitor. |
-| `TRASHCAN_EMOJI` | The emoji to use for the trashcan during paginated embeds |
+| `TRASHCAN_EMOJI` | The full emoji to use for the trashcan. Format should be like the output of `\:emoji:`. |
 
 
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