Update README.md

[wellencamass]

make examples for readme

Description

Please add a short description of pull request contents.
If this PR addresses an existing issue, please add the issue number below.

Fixes: #(issue number)

Additonally

• If this is the first time you are contributing to ffuf, add your name to CONTRIBUTORS.md.
  The file should be alphabetically ordered.
• Add a short description of the fix to CHANGELOG.md

Thanks for contributing to ffuf :)

[joohoi]

The text in the changed spots is actually pulled from the ffuf help text. I also think that it would probably be more efficient to write about the different filtering options in a more elaborate way and maybe under a specific subtitle in the README instead.