Update acknowledgements.md

documentation/docs/acknowledgements.md

@@ -3,4 +3,4 @@ Please add the following acknowledgment if you use our package in your work.
 "This work has made use of Infrared Guide Star Catalog (IRGSC) developed 
 as a part of the Thirty Meter Telescope (TMT) project."
 If you have any questions or suggestions for improvements to this repo,
-please email: [email protected]
+please email: [email protected]