Issue/feature addressed

Obsolete package names for linux exists and new packages were missing

Proposed solution

updated Debian, Ubuntu and Fedora packages in the user-guide and removed a comment related to Buster in CommMpi.cpp

N/A

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~~Functions and classes, or changes to them, are documented.~~
User guide/documentation is updated.
Changelog is updated.
~~Suitable tests added for new functionality.~~
~~Contributed code is correctly formatted. (See the ~~contributing guidelines~~).~~
~~License added to any new files.~~
No extraneous files have been added (e.g. compiler output or test data files).