Task/improve footer

[MiXiBo]

Resolves

Footer changes:

• add selected communities
• fix 'Contact Us' link which pointed to Twitter to 'contact@koinos.group'
• add Documentation, Learn Koinos and Block Explorer links
• Change 'Others' into 'Insides'
• update footer date to 2024

Brief description

Checklist

• [x] I have built this pull request locally
• [ ] I have ran the unit tests locally
• [x] I have manually tested this pull request
• [x] I have reviewed my pull request
• [ ] I have added any relevant tests

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