Feat/extended input example

[rustem-nasyrov]

Close #3108

Description

• Added currencies exchange example to show customizability.
• Renamed class in the inner-prepend slot.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any feature but make things better)

[m0ksem]

Looks good. Would be nice to have less html. I belive it can be done with one flex parent, without grid.