Update README.md

README.md

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 * Some authorizations by authors can be found [here](https://github.com/bmatthiesen/IRS-continuous/issues/1) and [here](https://github.com/emilbjornson/IRS-relaying/issues/1).
 
 * We have WeChat group for RIS(IRS). If you want to join, please send your WeChat ID to kewang0225@gmail.com. In the email, please state your real NAME and UNIVERSITY (it's a must for some reasons). 
-* We also have Facebook group for RIS, the link is https://www.facebook.com/groups/1400235907027708
+* We also have Facebook group for RIS(IRS), the link is https://www.facebook.com/groups/1400235907027708
 
 |No.| Paper Title | Authors | 
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