Fix typo in suffix(while:) description

[21sagge]

Fixes a grammar typo in Guides/README.md: "all element pass" -> "all elements pass" in the suffix(while:) description.

Checklist

• I've added at least one test that validates that my change is working, if appropriate
• I've followed the code style of the rest of the project
• I've read the Contribution Guidelines
• I've updated the documentation if necessary

[wallawonka]

@21sagge please if you don't mind check the first box in the checklist and this PR should be good to go!

The "if appropriate" fits perfectly with your changes. Even though you didn't write tests, it is not appropriate for your changes that already count with 2 approvals.

If I'm not mistaken that would make the Checklist fully complete.