remove redundant . from Scala 3 coursier download instructions

Author: soronpo

_includes/downloads-scala3.html

@@ -16,7 +16,7 @@ <h2>Ways to Install This Release</h2>
         Using <a
           href="https://docs.scala-lang.org/getting-started/index.html#using-the-scala-installer-recommended-way">Coursier
           CLI</a>, run:<br>
-        <code>cs install scala:{{page.release_version}} && cs install scalac:{{page.release_version}}</code>.
+        <code>cs install scala:{{page.release_version}} && cs install scalac:{{page.release_version}}</code>
       </li>
       <li>
         Download the Scala binaries for <strong>{{page.release_version}}</strong> at <a