chore: more funding updates in the readme to remove issuehunt and feature Tip4Commit

[activescott]

This updates the readme to remove issuehunt funding source and clarify usage of Tip4Commit.

Please fill out the following checklist:

• [x] Added tests for any bug fixes that changed existing code
• [x] Added tests for any new behavior
• [x] All unit tests are passing (please make sure all tests are passing for your branch/PR at https://ci.appveyor.com/project/activescott/lessmsi/history )

n/a since this is doc updates only and no code changes.

[activescott]

😓 . Good catches. I shouldn't have been in such a hurry :)