Add sponsorship links

[oozcitak]

Please include a summary of the change and which issue is fixed. Fixes # (issue number)

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Notes (delete after reading):

• Breaking changes sould rarely be necessary. If this change introduces a breaking change, make sure you have a very good reason for it.
• Please make sure this change is thoroughly tested. Add your tests to the test folder in a relevant sub folder. If this pull request is a bug fix, add a test specific to the fixed issue in the test/issues sub folder. If this change decreases code coverage you may be asked to add additional tests.