Fix MySQL Workbench links in README.md

[Deantwo]

Updated links to point to the official MySQL Workbench website. Since the old mysqlworkbench.org website seems to be gone.

[Deantwo]

The image in the README.md also doesn't seems to work, it just returns "Forbidden" for me.
But I couldn't seem to fix that, it might be an issue on the source dev.mysql.com webpage itself when connected through GitHub's Camo system, since can open the link to the image normally just fine. Or maybe it is some GitHub issue I don't understand.

• https://camo.githubusercontent.com/eca04d0211287defae87851837cc31ddbf98a79219781da32cc5f24a8d394e54/68747470733a2f2f6465762e6d7973716c2e636f6d2f646f632f776f726b62656e63682f656e2f696d616765732f77622d686f6d652d73637265656e2d6e65772e706e67
  • "Forbidden"
• ![test](https://dev.mysql.com/doc/workbench/en/images/wb-home-screen-new.png)
  • 

[mysql-oca-bot]

Hi, thank you for submitting this pull request. In order to consider your code we need you to sign the Oracle Contribution Agreement (OCA). Please review the details and follow the instructions at https://oca.opensource.oracle.com/
Please make sure to include your MySQL bug system user (email) in the returned form.
Thanks

[Deantwo]

If I was contributing to more than just the README, I would maybe go through the trouble of telling my boss.

I don't even know if it is the correct links I changed it to. Best someone else makes these changes instead I guess.