README: Add missing punctation (#228)

README.md

@@ -5,7 +5,7 @@ The `ClusterManager.jl` package implements code for different job queue systems
 > [!WARNING]
 > This package is not currently being actively maintained or tested.
 >
-> We are in the process of splitting this package up into multiple smaller packages, with a separate package for each job queue systems
+> We are in the process of splitting this package up into multiple smaller packages, with a separate package for each job queue systems.
 >
 > We are seeking maintainers for these new packages. If you are an active user of any of the job queue systems listed below and are interested in being a maintainer, please open a GitHub issue - say that you are interested in being a maintainer, and specify which job queue system you use.