add period

Author: ConnorLand

content/en/docs/releasenotes/studio-pro/lts-mts.md

@@ -99,7 +99,7 @@ Release notes for any current MTS versions are marked with an MTS badge (<text c
 
 Mendix MTS versions offer a balance between getting the latest and greatest Mendix has to offer every month, and security and stability.
 
-Recommended MTS upgrade cycle: 6 to 18 months
+Recommended MTS upgrade cycle: 6 to 18 months.
 
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 Mendix recommends using the latest patch version of the release as this will contain the latest fixes.