minor #653 Update community support channels (vvasiloi)

This PR was merged into the 1.12-dev branch.

Discussion
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Copied from https://github.com/Sylius/Sylius

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547f284 Update community support channels
62d8e2f Merge branch 'Sylius:master' into vvasiloi-patch-1

README.md

@@ -68,7 +68,7 @@ If you want to report a bug or suggest an idea, please use [GitHub issues](https
 Community Support
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-Have a question? Join our [Slack](https://slackinvite.me/to/sylius-devs) or post it on [StackOverflow](http://stackoverflow.com) tagged with "sylius". You can also join our [group on Facebook](https://www.facebook.com/groups/sylius/)!
+Get Sylius support on [Slack](https://sylius.com/slack), [Forum](https://forum.sylius.com/) or [Stack Overflow](https://stackoverflow.com/questions/tagged/sylius).
 
 MIT License
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