updated CHANGELOG.md and CITATION.cff

[tscheypidi]

Purpose of this PR

• updated CHANGELOG.md and CITATION.cff to be prepared for new developments

Performance loss/gain from current default behavior

• does not apply

Type of change

• Bug fix (Change which fixes an issue).
• New feature (Change which adds functionality).
• Minor change (Change which does not modify core model code i.e., in /modules).
• Major change (fix or feature that would change current model behavior).

How Has This Been Tested?

• Runs using starting script which tests current defaults (using test_runs.R).
• Runs using starting script which successfully runs the same scenarios as in test_runs.R but with the changes from PR.
• (If applicable) Runs using different scenarios/mappings which are not the default (12 regions/c200 clusters).

Additions or Changes to default configuration (default.cfg):

Additions are the introduction of new model components in default config

Changes are deletion or updates to the existing model components in default config

• Realizations:
• Scenario switches:
• Scalars/Constants:
• Model interfaces:
• Others:

Checklist:

• Self-review of my own code.
• Added changes to CHANGELOG.md
• No hard coded numbers and cluster/country/region names.
• The code doesn't contain declared but unused parameters or variables.
• In-code comments added including documentation comments.
• Compiled and checked resulting documentation with goxygen::goxygen() for the new/updated parts.
• Changes to magpie4 R library for post processing of model output (ideally backward compatible).

Special comments/warnings

• nice to have the template now in place by default!

[abhimishr]

👀 👍