Update README.md - remove outdated links

[djryanash]

Thank you for taking the time to work on a Pull Request for this project!

To ensure your PR is dealt with swiftly please check the following:

• Your submissions are formatted according to the guidelines in the contributing guide
• Your additions are ordered alphabetically
• Your submission has a useful description
• The description does not end with punctuation
• Each table column should be padded with one space on either side
• You have searched the repository for any relevant issues or pull requests
• Any category you are creating has the minimum requirement of 3 items
• All changes have been squashed into a single commit

[djryanash]

Deleted some entries with dead links.