removed a space to fix broken wiki link

README.md

@@ -20,7 +20,7 @@ We have detailed installation instructions in our wiki:
 Upgrading
 ---------
 
-If you are upgrading from a previous version of ShareLaTeX, please see the [Release Notes section on the Wiki] (https://github.com/sharelatex/sharelatex/wiki/Home) for all of the versions between your current version and the version you are upgrading to.
+If you are upgrading from a previous version of ShareLaTeX, please see the [Release Notes section on the Wiki](https://github.com/sharelatex/sharelatex/wiki/Home) for all of the versions between your current version and the version you are upgrading to.
 
 
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